Coaxial-flow heat transfer structures for use in diverse applications

ABSTRACT

A coaxial-flow heat exchanging structure having a proximal end and a distal end for exchanging heat between a source of fluid at a first temperature and the environment (e.g. air, ground, water, slurry etc.) at a second temperature. The coaxial-flow heat transfer structure comprises: a thermally conductive outer tube section, and an inner tube section having an inner flow channel and being coaxially arranged within the outer tube section. An outer flow channel is formed between the inner and outer tube sections, and helically-extending turbulence generator is provided along the outer flow channel, so as to create turbulence along the flow of heat exchanging fluid flowing between the inner and outer flow channels, and thereby increasing the heat transfer through the walls of the outer tube section to the ambient environment.

RELATED CASES

This Application is a Continuation of copending U.S. application Ser.No. 11/372,224 filed Mar. 9, 2006; which is a Continuation-in-Part ofcopending U.S. application Ser. No. 11/076,428 filed Mar. 9, 2005; eachsaid Application being owned by Kelix Heat Transfer Systems, LLC ofTulsa, Okla. and incorporated herein by reference as if fully set forthherein.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a novel method of and apparatus fortransferring heat using heat exchanging fluids that are safely isolatedfrom the environment above and below the Earth's surface and circulatedwithin a sealed heat exchanging structure so as to improve the heattransfer performance of aqueous-based fluid heat transfer systems,wherein the ground, a lake, a river, or sea water is used as the primaryor secondary heat sink or heat source in the sealed heat exchangingstructure.

2. Brief Description of the State of Knowledge in the Art

The development of refrigeration processes, associated equipment, andtwo-phase chemical refrigerants evolved primarily in response tomankind's need to preserve food. Over the years, several different kindsof heat transfer systems have been developed for dissipating heatremoved from the food to the exterior of the food storage container.

One type of heat transfer system is a typical refrigeration system whichincludes an evaporator for absorbing heat from one location, a condenserfor dissipating heat to another location, a compressor for compressingthe vaporous two-phase refrigerant exiting the evaporator for deliveryinto the condenser where the refrigerant is condensed back into aliquid, and a two-phase throttling device connected to the evaporatorinlet for receiving the liquid refrigerant and refrigerant expansion, tocomplete a refrigeration cycle.

Condensers can be constructed in various configurations, namely: as anarrangement of tubing with air-cooled fins, or as a water-cooled “tubeand shell configuration”.

In FIGS. 1 and 1A, the fluid flow characteristics of conventional tubingused in heat exchangers is schematically depicted. FIG. 1 illustrateshow the velocity of a fluid traveling through a tube decreases from thecenter of the tube towards the inner surface of the tube. As shown,fluid enters tube A through inlet opening C. A laminar fluid flowprofile D is caused by friction along a boundary layer E on the innersurface of the tube A. In the general, the annular region of flow B doesnot contain eddy currents during laminar flow. The shape of the laminarfluid flow profile D is influenced by the viscosity of the fluid passingthrough the tube. Fluids having lower viscosities cause a thinnerboundary layer E to form, whereas fluids with higher viscosities, suchas propylene glycol mixture (anti-freeze) and other viscosity increasingadditives, causes a thicker boundary layer E to form, which reduces heattransfer. Fluids with lower viscosities, such as pure water, cantransition into turbulent flow at lower fluid velocities.

Turbulence can be regarded as a highly disordered motion of matter (e.g.water, air etc.) resulting from the growth of instabilities in aninitially laminar flow, and it is generally agreed that the transitionfrom laminar to turbulent flow may be described as a series of eventsthat take place more or less continuously. Additionally, it is knownthat turbulent fluid flow characteristics, due to eddy currents, canincrease heat transfer across heat conducting surfaces. During turbulentflow, the annular flow region contains eddy currents which increase heattransfer. Fluids with higher viscosities, such as propylene-glycol,require higher fluid velocities in order to transition into turbulentflow. This requires more pump energy to transfer the same quantity ofheat energy as pure water. Also, tubing with a rough inner surfaceallows the fluid to transition into turbulent flow at a lower fluidvelocity.

FIG. 1A illustrates how flow velocities within annular regions of fluidflow B, C and D are influenced by frictional forces generated fromboundary layer E. Within the boundary layer E, against the inner surfaceof the tube, the velocity of the heat transfer fluid can be zero. In theannular flow region B, the fluid is shown moving at 3 feet per minute,and faster in areas closer toward the annular flow region C, which has aflow velocity of 3 feet per minute. The fluid in the annular flow regionD has the highest velocity of 10 feet per minute. Typically, thereduction in fluid flow velocity adjacent the inside surface of a tuberesults in a decrease in the rate of heat energy transferred from thefluid into the tube material.

The primary method of compensating for such heat transfer constraints(imposed by laminar fluid flows through conventional tubing structures)has been to use larger tubes and more powerful pumps in conventionalheat transfer systems, which has resulted in higher installation costsat lower operating efficiencies.

At this juncture, it is appropriate to continue surveying prior artsystems with such considerations in mind.

In the water-cooled tube and shell condenser, the rate of heat transferbetween the refrigerant in the refrigeration-sealed system, and thewater flowing around the tube and shell condenser tube, is much higherthan the rate of heat transfer between the refrigerant in therefrigeration-sealed system and air flowing around the tubes of theair-cooled fin and tube condenser. A water-cooled tube and shellcondenser is normally connected with pipes to a cooling tower and awater pump. The heat is absorbed by the water while circulated throughthe condenser. The heat in the water entering the cooling tower is thendissipated into the atmosphere from the water, completing a closed-loopwater-cooled refrigeration process.

Environmental concerns have caused strict restrictions to be placed onwater-cooled tube and shell condenser systems utilizing a water pump togather water from natural sources such as a lake, a river, sea water,and other fluid systems, for circulation through the water-cooled tubeand shell condenser of such heat transfer systems. Environmentalcontaminations vary but are mostly related to chemical concentrationsand temperature variations being dispensed into the water source.

A water-cooled tube and shell condenser can be connected to aground-source heat transfer well using pipes, to dissipate heat into theEarth. In various manufacturing processes, the required operatingtemperature and capacity (i.e. volume) of heat transfer fluid circulatedthrough the ground source heat transfer well, may not require addingrefrigeration to the system.

Ground loop heat transfer installations vary from trenched horizontalloops to multiple vertical loops. In FIGS. 1B and 1C, verticalinstallations are schematically illustrated in two different heattransfer modes.

In FIG. 1B, a (field assembled) conventional “U” tube type heat transfertube is shown buried in the Earth for the purpose of dissipating heatenergy from the system into the Earth. Typically, tube sections G and Iare buried beneath the Earth a few inches apart from one another. Duringoperation, a heat transfer fluid flows into inlet F in a laminar mannerat 110 degrees Fahrenheit, and is forced to flow down tube section G.Heat energy in the laminar flowing fluid is transferred into the Earthat 55 degrees Fahrenheit, along the entire outer surface of the tube G.As illustrated, a portion of the heat from tube section G is actuallytransferred into tube section I after the heat transfer fluid hasreversed its flow direction when flowing along elbow section H. Usingthis ground loop arrangement, the net amount of heat energy actuallytransferred into the Earth is diminished due to the heat transfer fromtube section G into tube section I. Thus, the overall heat transfercapacity offered by this system design is significantly diminished dueto (i) the laminar flow profile of the heat transfer fluid within the“U” tube construction (illustrated in FIG. 1), and (ii) the comminglingof heat energy exchanges between underground tube sections G and tube I.

In FIG. 1C, a (field assembled) conventional “U” tube type heat transfertube is shown buried in the Earth for the purposes of collecting heatenergy therefrom. In this configuration, a heat transfer fluid flows at40 degrees Fahrenheit into inlet F in a laminar manner, and is forced toflow down tube section G into the Earth. Along the entire outer surfaceof the tube section G, heat energy is transferred from within the 55degree Fahrenheit Earth, into the heat transfer fluid maintained at 40degree Fahrenheit. Since the 15 degree Fahrenheit temperature differencebetween the heat transfer fluid inside tube section G is higher thanthat of the heat transfer fluid occupying tube section I, more heatenergy is absorbed by tube section G than is absorbed by tube section I.Also, a portion of the heat energy transferring into tube section Goriginates from tube section 4 and is actually transferred into tubesection G after the heat transfer fluid has reversed its flow directionalong elbow section H. Again, the overall heat transfer capacity offeredby this system design is significantly diminished due to (i) the laminarflow profile of the heat transfer fluid within the “U” tube construction(illustrated in FIG. 1), and (ii) the commingling of heat energyexchanges between underground tube sections G and tube I.

Residential and commercial comfort air conditioning systems using“air-cooled condensers” are also well known in the art. Air-cooledcondensers are also used extensively world-wide on air conditionersemploying heat pumps. In contrast, “water-cooled tube” and shellcondensers are typically used in large tonnage commercial and industrialapplications such as in high-rise buildings, natural gas dehydration,and liquefied natural gas gasification systems.

A heat pump, originally called a reverse refrigeration system, reversesthe refrigeration process through the use of sealed system valves andcontrols causing the evaporator to dissipate heat while causing thecondenser to absorb heat. In its cooling mode of operation, an airconditioning system employing a ground-source heat-pump will dissipateheat into the Earth while, and absorb heat from the Earth in its heatingmode of operation.

Over the years, the ground/water source type heat pump has proven veryuseful as a very efficient form of heating and cooling technology. Theuse of ground/water source type heat pumps have three distinctadvantages over air source type heat pumps, namely: during the peakcooling and heating seasons, the ground/water source usually has a morefavorable temperature difference than the atmospheric air; theliquid-refrigerant exchanger on the heat pump permits a closertemperature approach than an air-refrigerant exchanger; and there is noconcern with frost/snow/ice/dirt buildup or removal on the heatexchanger.

In general, prior art heat pump installations have employed undersizedground loops (constructed using conventional U type tubing) becauserefrigerant-based fluids can provide a sufficient temperature differencebetween the fluid and the ground so that enough heat is transferred toand from the ground to match the heating/cooling load on the heat pump.However, the use of undersized ground loops is also known to reduce theSEER rating of the heat-pump system. Also, the design goals of prior artheat pump systems have been to minimize the length of the metal pipe(i.e. tubing) used in the ground loop, while just passing the minimumstandards for efficiency.

When prior art heat pump systems experience peaks or spikes inheating/cooling loads during daily operations, thermal storage solutionsare oftentimes added to the system in order to average the load over thetime period of interest. Thermal storage solutions also help reduce thecost of the ground loop by allowing the loop to be sized for the averagebase load over the day, week or season. In fact, many large buildingsand residences use thermal storage solutions in order to reduce the costof heating and cooling by (i) using less expensive night-time electricalloads to heat/cool the thermal mass, and then (ii) using the thermalmass to heat/cool the building during the day. In order to reducecapital cost of the heat pump system, prior art heat pump systeminstallations often use the metal rebar in the foundation or piling as amajor part of the thermal mass of the ground loop portion of the heatpump system.

Ground source or water source type heat pumps can use a closed or openloop as a heat exchanger. Open loops include water circulated to coolingtowers; water circulated between wells, geothermal steam wells, watercirculated in a body of water such as a river or lake. Closed loopsinclude aqueous-based fluids and refrigerant-based fluids circulated incooling/heating coils that transfer heat to air, water, and ground. Mostpower plants use at least one open loop to generate steam (the burnerexhaust) and one open loop (cooling towers or lake) to condense thesteam back to water. The de-ionized steam source water is preserved in aclose loop to prevent scale buildup in the heat exchanger. Mostconventional refrigerators, freezers and air conditioners use a closedloop of refrigerant to cool the load and an open loop of external air tocondense the refrigerant.

The shortcomings and drawbacks of using air to transfer heat from thecondenser coil is that air requires a high temperature differential anda large condenser coil surface area to achieve reasonable heat transferrates. The high temperature differentials translate to a high-pressuredifferential which implies higher energy costs to transfer a unit ofheat. When a heat pump uses a liquid, from a water or ground loop, totransfer heat from the condenser coil, a smaller coil and a lowertemperature and pressure differential can be used to transfer the sameunit of heat as the air cool condenser coil which, in turn, improvesefficiency and reduces energy costs.

When closed loops are used in the ground or water source of a heat pumpsystem, there is a trade off between using (i) metal tubing with a highheat transfer coefficient (i.e. which is subject to corrosion andthermal expansion), and (ii) plastic tubing with a low heat transfercoefficient, which is resistant to corrosion and thermal expansion. Foraverage soil conditions, plastic tubing usually will require about three(3) times the heat transfer area of the metal tubing to maintain anequivalent heat transfer rate. Metal tubing is usually reserved forrefrigerant-based fluids due to the high fill pressures and thereactivity of the refrigerant with plastic tubing.

While protective coatings and grouting can reduce the corrosion rates ofmetal tubing, pin holes in the coating or grout can actually concentratethe anode corrosion rate in the pin-hole area. Electrical measurementshave shown that circulating aqueous based fluids between the ground loopand heat pump can cause the flow of a low level current between thebuilding and the ground.

In accordance with convention, a close-loop ground/water source heatpump can use a refrigerant based fluid or an aqueous-based fluid. Withrefrigerant-based fluids, the heat pump can use a high differentialtemperature to transfer heat between the ground and the fluid in thetubing, but extra energy load reduces the SEER rating of the heat pumpsystem. Metal tubing is used to contain the pressurizedrefrigerant-based fluid and minimize the volume of refrigerant in theground loop system due to the high heat transfer coefficient of themetal.

As discussed in U.S. Pat. No. 5,025,634 to Dressler, refrigerant basedfluids have very high maintenance cost when a small leak develops in theground/water loop and a very high environmental impact when there is arelease of the refrigerant. Also, over a long period of time, fieldexperience has shown that high pressure head loss can develop in theclosed ground/water source loop when lubricating oil from the compressorcollects low spots in horizontal loop or at the bottom of the bore holein vertical loop.

With most aqueous-based fluid ground/water source loops, the heat pumpuses a small close-loop refrigerant heat exchanger to transfer heat toor from the aqueous fluid. The small heat exchanger reduces the capitalcost of the heat pump and reduces the chances of refrigerant releases tothe environment. In areas with ground movement, such as earthquakeszones, subsidence bowls, and deep freeze/thaw zones, the boreholethermally-conductive outer tube and transfer piping can develop leaksdue to repeated damage over time as discussed in U.S. Pat. No. 4,993,483to Kurolwa.

As disclosed in U.S. Pat. No. 4,644,750 to Lockett and Thurston and inU.S. Pat. No. 4,325,228 to Wolf, a horizontal ground loop's performanceis affected by fluctuation in atmospheric surface temperature and soilmoisture content, whereas, the ground loop based on multiple bore holeshas a stable fluid temperature and heat transfer coefficient for bothheating and cooling thermal loads. For heat and cooling loads located onsmall land surfaces or arid land, the ground loop heat exchanger basedon multiple bore holes can provide a heat pump with a stable heat sinkor source as described in U.S. Pat. No. 4,392,531 to Ippolito.

The first major improvements to ground loop fluid heat transfer usingmetal tubing and refrigerant based fluids are disclosed in U.S. Pat. No.5,816,314 to Wiggs et. al, U.S. Pat. No. 5,623,986 to Wiggs, U.S. Pat.No. 5,461,876 to Dressler, U.S. Pat. No. 4,867,229 to Mogensen, and U.S.Pat. No. 4,741,388 by Kurolwa where metal tubing was bent into a helixshape to increase heat transfer between the refrigerant and the ground.These five patents disclose that the ‘vertical helical heat exchanger’or the ‘bore-hole helical heat exchanger’ provides the heat pump with astable heat sink or source for heating and cooling. The shortcoming ofthese designs is the increased capital cost of helical bending of thetubing and the increased installation cost involved in running benthelical tubing in a deviated well.

Another popular technique used in prior art heat pumps involvesinsulating the metal, fluid-return tube from the bottom of the bore holeso to prevent heat transfer from incoming fluid, which significantlyimproves the heat exchanger performance. The deficiency of such priorart insulating methods has caused a significant increase in installationcosts and a significant increase in capital cost associated withinsulating materials. Notably, as the return line was far enough awayfrom the loop to not cause any significant thermal interference,insulating the fluid return tube was not required for earlier horizontalground loop heat exchangers.

U.S. Pat. No. 5,623,986 to Wiggs also discloses that external helicallyshape fins can be used to drill short vertical heat exchangers intosand-loam soils or mud bottoms, but field experience has shown thatthere is toO much fin damage when installing vertical heat exchangers inhard rock/ground surfaces.

U.S. Pat. No. 5,937,665 to Kiessel et al., discloses other improvementsto refrigerant based groundloops, wherein an air heat exchanger is usedto the system to reduce the load on the ground loop.

U.S. Pat. No. 6,138,744 by Coffee discloses using a large storage tankof water to a horizontal ground loop that is continuously replenished byan external water source such as water well. This technique involvescombining an open water loop and a lose ground loop.

U.S. Pat. No. 6,615,601 by Wiggs discloses combining a solar heatingloop and a water evaporative cooling loop to the ground loop so as tosupplement the heating and cooling load.

U.S. Pat. No. 6,212,896 to Genung discloses a ground loop with largewell bores to make room for a vertical thermal siphon to enhance theheat transfer in the large well bore. The shortcoming of this idea isthat the heat is transfer to the thermally-conductive outer tube wallwith a laminar flow of fluid.

U.S. Pat. No. 6,672,371 to Amerman et al. created a ground loop bydrilling multiple well bores from one pad and using plastic U-tubes forthe heat exchanger. By using many plastic U-tubes with low heat transferin series, an equivalent metal heat exchanger performance can beachieved in the ground loop.

Also, U.S. Pat. No. 6,789,608 to Wiggs discloses a technique forextending the performance of the U-tube heat exchanger by installing aninsulating plate between the tubes to make two close separate half wellswith minimal thermal interference between each well.

Thus, while various advances have been made in heat transfer systemdesign and implementation, there is still a great need in the art for animproved method of and apparatus for transferring heat from above orbelow the Earth's surface using a sealed fluid circulation system, whileovercoming the shortcomings and drawbacks of prior art methodologies andequipment.

SUMMARY AND OBJECTS OF THE PRESENT INVENTION

Accordingly, it is a primary object of the present invention is toprovide a coaxial-flow heat exchanging (i.e. transferring) structure forinstallation in an ambient environment and facilitating the transfer ofheat energy between an external heat energy producing system and theambient environment, while overcoming the shortcomings and drawbacks ofprior art methodologies.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure having a proximal end and adistal end for exchanging heat between a source of fluid at a firsttemperature and the environment (e.g. ground, water, slurry, air, etc.)at a second temperature.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure having an input port, provided atthe proximal end, for receiving a heat (energy) transferring or carryingfluid at a first temperature from the external heat energy producingsystem, and an output port, also provided at the proximal end, foroutputting the heat transferring fluid at a second temperature to theheat energy producing system or the like.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure further comprising an inner tubesection having an outer wall surface extending between the proximal anddistal ends, and supporting an inner flow channel having a substantiallyuniform inner diameter along its entire length, and into which the heatexchanging fluid can be introduced from the input port, and along whichthe heat exchanging fluid can flow in a substantially laminar mannertowards the distal end.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure further comprising an outer tubesection, disposed coaxially around the inner tube section, and having aninner wall surface extending between the proximal and distal ends, andthe outer tube section being in thermal communication with the ambientenvironment.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure, wherein an outer flow channel ofhelical geometry is provided between the outer wall surface of the innertube section and the inner wall surface of the outer tube section, andcapable of conducting heat exchanging fluid from the distal end, alongthe outer flow channel towards the proximal end, and exiting from theoutput port.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure, wherein a turbulence generatingstructure is disposed along a substantial portion of the length of theouter flow channel so as to introduce turbulence into the flow of theheat exchanging fluid flowing along the outer flow channel, from thedistal end towards the proximal end, and thereby improving the transferof heat energy between the heat exchanging fluid and the ambientenvironment along the length of the outer flow channel.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure, wherein the turbulencegenerating structure comprises a helically-arranged fin structuredisposed along a substantial portion of the outer flow channel.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure, wherein the helically-arrangedfin structure is mounted to the outer surface of the inner tube section.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure, wherein the laminar fluid flowalong the inner tube section provides an insulating effect between thewall of the inner tube section and the inner flow channel.

Another object of the present invention is to provide such acoaxial-flow heat exchanging structure, for sinking heat into the groundduring cooling operations, or sourcing heat from the ground duringheating operations.

Another object of the present invention is to provide a heat pump systememploying the coaxial-flow heat exchanging structure of the presentinvention, wherein the heat transfer performance of aqueous-based fluidheat transfer is substantially improved, and wherein the ground, a lake,a river, or sea water can be used as the primary or secondary heat sinkor heat source.

Another object of the present invention is to provide such a heat pumpsystem which may or may not incorporate the use of a refrigerationsubsystem.

Another object of the present invention is to provide such a heat pumpsystem, wherein the heat transfer performance of aqueous-based fluids issubstantially improved by using heat-pump heating/cooling heatexchangers where the ground is used as the primary or secondary heatsink/source in a closed loop.

Another object of the present invention is to provide such a heat pumpsystem, wherein capital/installation cost of the total heat pump systemis substantially reduced.

Another object of the present invention is to provide a heat pump systememploying a coaxial-flow heat exchanging structure which is installedinto the Earth, a lake, a river, sea water or other heat sink or heatsource to absorb heat or dissipate (i.e. radiate) heat energy into orfrom the heat transfer fluid by isolating the heat transfer fluidentering the center insulating tube, from the helically flowing fluidexiting the assembly. The interior surface of the thermally-conductiveouter tube section is the primary heat transfer surface of thecoaxial-flow heat exchanging assembly.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure that can be used in diverse kinds of heat pumpsystems, wherein the coaxial-flow heat exchanging structure can bemanufactured as a primary system, a system sub-component, or asub-component kit.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure for use in a heat pump system, wherein theheat exchanging surface area of the structure is increased by flutingthe plastic surface of the outer thermally-conductive outer tube and byincreasing the length of the bore into the ground (bore length) as aresult of drilling deviated-type wells in aquifer zones of the Earth.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure for use in a heat pump system, wherein as theheat transfer surface area and the contact volume of the ground/watersource loop increase, the circulating fluid temperature will approachthe average ground temperature through out the full duration of theheating and cooling seasons.

Another object of the present invention is to provide such a heat pumpsystem, wherein a uniform bore hole is drilled into an aquifer zone anda smooth metal pipe or a fluted plastic pipe is installed within thebore hole so that the coaxial-flow heat exchanging structure of thepresent invention can be constructed within most geologic ground types,without major changes in installation/construction procedures.

Another object of the present invention is to provide a method of andapparatus for enhancing the heat transfer in aqueous based fluidground/water source loop systems so that a low differential temperature,high mass-rate heat pump can be used to cool or heat a thermal load froma building or industrial process.

Another object of the present invention is to provide a ground/watersource heat-pump system that has a SEER rating that exceeds air-sourceheat pump systems and ground-source heat-pump systems using arefrigerant-based heat-transfer fluid.

Another object of the present invention is to provide an improved heatpump system, wherein the aqueous-based fluid contains a biodegradableanti-freeze and dye to minimize the environmental impact of leaks in theground loop and improve leak detection in the ground loop multi-wellgrid.

Another object of the present invention is to provide apparatus formanufacturing the helically-finned tubing employed within thecoaxial-flow heat transfer (exchanging) structure of the presentinvention.

Another object of the present invention is to provide a coaxial-flowheat-transfer structure, wherein the temperature of the heat transferfluid is substantially maintained until it reaches the bottom of thewell, so that a higher temperature difference is maintained between theturbulent flowing fluid in the outer flow channel between the inner tubesection and the outer tube section, thereby increasing the rate of heattransfer into the inside wall of the outer tube section and consequentlyinto the grout cement and eventually into the Earth, rock, and aquifer,if an aquifer exists.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure which employs a fluid return and injectionmanifold employing a plurality of small holes formed in a cap structureto achieve a low friction-created pressure drop, or alternatively, asingle medium size hole for achieving a higher friction-created pressuredrop.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure which employs a fluid return and injectionmanifold cooperating with a compression-ring type cap installed on theproximal end of the coaxial-flow heat exchanging structure, to seal thesystem and prevent fluid leaks.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure which employs a fluid return and injectionmanifold cooperating with a clamped-type cap installed on thecoaxial-flow heat exchanging structure, wherein the cap has an O-ring orU-ring seal around the proximal portion of the thermally-conductiveouter tube section to prevent fluid leaks.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein a manifold is joined to a pluralityof small holes formed in a cap portion provided on the proximal portionof the outer tube section, so that heat exchanging fluid exitsperpendicular to central axis of the thermally-conductive outer tubesection.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein a manifold is joined to a pluralityof small holes formed in a cap portion provided on the proximal portionof the outer tube section, so that heat exchanging fluid exits parallelto central axis of the thermally-conductive outer tube section.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein a pair of tube fittings are welded orfused to the side of the thermally-conductive outer tube section, forthe injection and returning heat exchanging fluids to the inner andouter flow channels realized therein.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, which is installed in a deviated well bore inthe Earth, wherein the horizontal section of the structure is drilledinto an aquifer zone and the vertical section thereof connects thehorizontal section back to the Earth's surface.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, which is installed in a near horizontallybored well in the side of a mountain, mesa, or hill, wherein the wellbore path is deviated to follow an aquifer zone if available at thesite, and wherein, for buildings with a deep basement or built on theside of a hill, the deviated well bores are drilled in the wall of thebasement.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, which is installed in a well bore that iscapped below the surface to prevent significant heat transfer to theground/water surface or atmosphere, and wherein for areas that havesignificant ice or freeze/thaw movement, the distribution pipes would beprotected against damage and, if possible, the well should be cappedbelow the frost line.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, which is installed vertically in foundationsor pilings of a bridge pier or like structure.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, which is installed horizontally in thefoundations or pilings of a building, bridge, or other structure.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, which is suspended horizontally in an aqueoussolution or mud.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, which is installed in a bridge component orpiling, wherein in earthquake areas, the pilings are wrapped in a metalsheath to prevent structural damage in the earthquake, and helicallyextending outer flow channels provide a ground/water source heat toprevent icing of the road way or sidewalks during the winter.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, which is installed within the Earth about aresidential home, wherein an optional thermal bank tank is provided fornight time operation when the electrical energy costs are cheaper, orfor daytime operation when solar cells can provide electrical energy.

Another object of the present invention is to provide a plurality ofcoaxial-flow heat exchanging structures installed below the ground so asto prevent icing or snow accumulation on side walks, bridges and heavilytraveled intersections or steeply pitched roads.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein sea water is used as the heat-pumpheat sink for gas dehydration and oil de-waxing, and wherein one or morecoaxial-flow heat exchanging structures of the present invention areinstalled in the ocean above the ocean floor, for the purpose ofextracting heat from the gas so as to cause the temperature thereof todrop, thereby condensing water vapor and/or light hydrocarbon vapors inthe gas stream.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein ballast water is used as theheat-pump heat sink for gas dehydration and oil de-waxing, and whereinone or more coaxial-flow heat exchanging structures of the presentinvention are installed in the ocean above the ocean floor, for thepurpose of extracting heat from the gas so as to cause the temperaturethereof to drop, thereby condensing water vapor and/or light hydrocarbonvapors in the gas stream.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, employed in a ground-loop heat exchangingsystem, designed for dehydrating, on shore, pipeline-quality gasproduced from remote off shore wells Another object of the presentinvention is to provide a coaxial-flow heat exchanging structure,installed in a ground-loop heat exchanger used in a natural gasdehydration and condensate separation system constructed on land for aplatform well or a gathering system.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure within a natural gas dehydration system,wherein the gas in the liquid separator is cooled to a temperature nearthe aquifer temperature, and then gas is cooled with a heat pump to atemperature near the gas hydrate temperature using a rotating heatexchanger.

Another object of the present invention is to provide a submarineemploying a coaxial-flow heat exchanging structure of the presentinvention installed within a seawater heat exchanging subsystem forcentralized air conditioning and equipment cooling.

Another object of the present invention is to provide a submarineemploying a coaxial-flow heat exchanging structure of the presentinvention installed within a seawater heat exchanging subsystem fordecentralized air conditioning and equipment cooling.

Another object of the present invention is to provide anair-conditioning system employing a plurality of coaxial-flow heatexchangers of the present invention, wherein the outer tubes of the heatexchangers are made of metal and are provided with external fins so asto provide maximum heat transfer with the ambient environment.

Another object of the present invention is to provide a plurality ofcoaxial-flow heat exchanging structures of the present inventioninstalled within a plurality of deviated wells, wherein eachcoaxial-flow heat exchanger is installed in thermally-conductive cement,and connected together using piping so as to form a heat pumpingnetwork.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein segmented, helically-extending finnedinner tube sections having alternating left and righted handed twistsare installed within thermally-conductive outer tube sections, so that amixing zone is provided for turbulently mixing the heat exchanging fluidflowing along the helically-extending outer flow channel, to break upboundary layers that may form on the outer flow channel wall surfaces,and thereby increasing the efficiency of the system to exchange heatenergy with the ambient environment.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein a segmented helically-finned innertube section, with integrated mixing zones, is installed in the outertube sections of the coaxial-flow heat exchanging structure.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein segmented helically-finned inner tubesections, with fluid mixing zones formed there-between, are realizedusing tube segments made of extruded pieces that are joined together byplastic couplings that are glued or welded together.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an inner tube section withhelically-finned segments applied to the outer surface thereof.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an inner tube section with wrap-aroundtype single fin segments applied thereabout so as to realizehelically-finned inner tube sections within the thermally-conductiveouter tube section of the structure.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an inner tube section with wrap-aroundsingle fin segments applied to the outer surface of the inner tubesection, wherein the wrap-around single fin segments have an integratedbase layer that has been extruded flat and parallel while heated to itsplastic point, and wherein the segment can be wrapped around a mandrelso as to provide the fin with a helical pitch to match the tubing orhose size to be employed within a coaxial-flow heat exchangingstructure.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an inner tube section with a pluralityof wrap-around single fin segments applied to the outer surface thereof,wherein said fin segments have a left hand twist.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an inner tube section with a pluralityof single helical fin segments installed on the outer surface thereof,and the inner tube section contained within the outer tube section, andprovided with a re-mixing zone between the helical fin segments for theturbulent mixing of heat exchanging fluid along a helically-extendingouter flow channel realized between the inner and outer tube sections.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an inner tube section supportingsegmented single helical fin segments, having alternating left andrighted handed twists, and providing a re-mixing zone between thehelical fin segments for the turbulent mixing of heat exchanging fluidalong a helically-extending outer flow channel realized between theinner and outer tube sections.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an inner tube section with multiple-finsegments applied about the outer surface thereof so as to realize ahelically-finned inner tube section employed in the coaxial-flow heatexchanging structure.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an inner tube section with multiple-finsegments applied about the outer surface thereof so as to realize thehelically-finned inner tube sections employed in the coaxial-flow heatexchanging structure.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an helically-finned that is formedusing plastic molding techniques.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an helically-finned inner tube sectionthat is formed using extrusion techniques.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an helically-finned inner tube sectionthat is formed using plastic molding techniques.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an helically-finned inner tube sectionconstructed from molded plastic fin segments, wherein the pitch on thefin segments is selected based on the amount of rotational fluid flowneeded in the helically extending outer flow channel formed between theinner and outer flow channels of the coaxial-flow heat exchangingstructure.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an helically-finned inner tube sectionconstructed from molded plastic fin segments, wherein tabs and slots areprovided on the base of the fin segments so as to snap together thesegments about the outer surface of the inner tube section, after whichthe connection points can be glued or welded together.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an helically-finned inner tube sectionconstructed from molded plastic fin segments, wherein at least one pairof the fin segments have the same twist directions within the outer tubesection for supporting a mixing zone along the helically-extending outerflow channel formed between the inner and outer tube sections.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein a pair of multi-finned segmentedtubing sections with (flow-guiding) fins having alternating twistdirections are installed within an outer tube section for supporting amixing zone along a helically-extending outer flow channel formedbetween the inner and outer tube sections.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure installed within a well bore formed in Earth,and surrounded by thermally-conductive cement containing carbon and/oraluminum oxide flakes, or metallic fibers or other thermal conductivityenhancing particles.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure installed in a well bore formed in the Earthand surrounded by thermally-conductive cement that was pumped within thewell bore and filled up the interstices of the well bore during theinstallation phase.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having an helically-finned inner tube section,a thermally-conductive outer tube section, and a fluid re-mixing zonealong an outer flow channel formed between the inner and outer tubesections, for mixing a helically-rotating fluid flowing there-along soas to increase the heat transfer efficiency of the system.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having a thermally-insulated inner tubesection, a thermally-conductive outer tube section and an outer flowchannel formed therebetween, wherein a plurality of rows of zig-zagingfluid turbulence generators/projections are provided as segments on theouter surface of the inner tube section for the purpose of generatingturbulence in the heat exchanging fluid flowing through the outer flowchannel.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having a thermally-insulated inner tubesection, a thermally-conductive outer tube section and an outer flowchannel formed therebetween, wherein a plurality of fluid turbulencegenerators/projections provided on the outer surface of the inner tubesection for the purpose of generating turbulence in the heat exchangingfluid flowing through the outer flow channel.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure having a thermally-insulated inner tubesection, a thermally-conductive outer tube section and an outer flowchannel formed therebetween, wherein the inner tube section and itsplurality of helically extending fins are formed by an extrusionprocess, and subsequently inserted within the outer tube section to formthe helically-extending flow channels between the inner and outer tubesections.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein the inner tube section has a singlehelically-extending fin structure, of discrete structure, disposed alongthe outer flow channel between the inner and outer tube sections, forthe purpose of generating turbulence in the flow of exchanging fluidalong the outer flow channel.

A coaxial-flow heat exchanging structure of the present invention,wherein the inner tube section has multiple rows of discrete finsegments helically-extending along the outer flow channel between theinner and outer tube sections, and formable as flexible planar segments(through modeling techniques) and then applied about the outer surfaceof the inner tube structure.

Another object of the present invention is to provide a coaxial-flowheat exchanging structure, wherein a continuous helically-extendingturbulence generating structure along the outer flow channel between theinner and outer tube sections.

These and other objects of the present invention will become apparenthereinafter and in the Claims to Invention.

BRIEF DESCRIPTION OF DRAWINGS

For a more complete understanding of how to practice the Objects of thePresent Invention, the following Detailed Description of theIllustrative Embodiments can be read in conjunction with theaccompanying Drawings, briefly described below, in which visualdescriptions are provided showing the installation of the presentinvention in the ground, water, air, and/or mud line environments, withlike reference numerals indicating like structures.

FIG. 1 is a schematic representation of a longitudinal cross-section ofa prior art tube section carrying a flowing fluid, illustrating alaminar fluid flow profile across the interior of the tube, in which thevelocity of the fluid traveling through the tube is maximum in thecenter of the tube and decreases from the center to the inner surface ofthe tube.

FIG. 1A is a schematic representation of a traverse cross-section of theprior art tube of FIG. 1, further illustrating that the frictionpresented at the boundary surface layer between the tube and the fluidcauses (i) a gradient in velocities across the tube (giving rise todifferent annular flow velocities), and (ii) a corresponding reductionin capacity of heat energy transfer from the fluid into the tube wallmaterial during fluid flow.

FIG. 1B is a schematic representation of a prior art “U” tube type heattransfer ground loop system buried in the Earth for the purpose oftransferring (i.e. sinking) heat energy into the Earth, and illustratingthat the overall capacity of the system to transfer heat energy into theEarth is diminished due to the heat energy exchange between adjacenttubes in the system.

FIG. 1C is a schematic representation of a prior art “U” tube type heattransfer ground loop system buried in the Earth for the purpose ofextracting heat energy from the Earth, and illustrating that the overallcapacity of the system to transfer heat energy into the Earth isdiminished due to the heat energy exchange between adjacent tubes in thesystem.

FIG. 2 is a schematic representation of a heat transfer system employingconventional mechanical heat transfer equipment, and at least onecoaxial-flow heat transfer (i.e. exchanging) structure of the presentinvention comprising (i) a thermally conductive outer tube section, and(ii) an inner tube section having an inner flow channel having asubstantially uniform inner diameter along its entire length and beingcoaxially installed within the outer tube section, and supportinghelically-arranged turbulence generating fins on its outer surface, soas to form at least one helically-extending outer flow channel betweenthe inner and outer tube sections, so that heat energy contained withina heat exchanging fluid flowing down the inner flow channel and alongthe helically-arranged outer flow channel, is exchanged through thewalls of the outer tube section and into the ambient environment.

FIG. 3 is a front elevated view showing a section of helically-finnedinner tube section used to create the helically-extending outer flowchannel between the inner and outer tube sections of the coaxial-flowheat exchanging structure of the present invention;

FIG. 4 is a back elevated view of the section of helically-finned innertubing shown in FIG. 3;

FIG. 5 is a front elevated view showing an inner tube sectionsupporting, on its outer surface, double sets of helically-extendingfins for use in creating a double helically-extending outer flow channelbetween the inner tube section and the thermally-conductive outer tubesection of the coaxial-flow heat transfer structure of the presentinvention.

FIG. 6 is a front view showing a central tube section inserted within aninner tube section supporting, on its outer surface, singlehelically-extending fin, for use in creating a singlehelically-extending outer flow channel between the inner tube sectionand the thermally-conductive outer tube section shown in FIG. 3;

FIG. 7 is the top view of a single helically-finned tube subassemblyshown in FIG. 6, wherein the gas gap between the central tube sectionand the helically-finned inner tube section provides thermal insulationto the heat transferring fluid flowing along the inner flow channel ofthe central tube section, and wherein the gap distance between the wallsof these tube sections remains substantially uniform along the length ofthe subassembly, due to a plurality of standoffs provided on the outersurface of the central tube section;

FIG. 8 is the front elevated view of an inner tube section supporting,on its outer surface, a single helically-extending (fluid-guide) finthat can be extruded with the inner tube section for small diameters, oralternatively can be extruded over a tube of larger diameter, whereinfor diameters exceeding 18 inches or 0.5 meters, the helically extendingfins can be rolled from flat stock and welded on the outer surface ofthe inner tube.

FIG. 9 is the top view of the single helically-finned tube subassemblyshown in FIG. 8;

FIG. 10 is the top view of the double helically-finned tube subassemblyshown in FIG. 5, designed for installation within a thermally-conductiveouter tube section of the coaxial-flow heat transfer structure of thepresent invention.

FIG. 11 is a front view of the central tube section that can beinstalled in the coaxial-flow heat transfer structure of the presentinvention, wherein its standoffs provide a gas gap needed for insulationbetween the central tube section and the helically-finned inner tubesection, and wherein the insulation gas can be argon, nitrogen, or evenethane.

FIG. 12 is the top view of a central tube section shown in FIG. 11;

FIG. 13 is an elevated front view of a helically-finned inner tubesection fitted with a thermally-insulated central tube section and ajoint collar for use in coaxial-flow heat transfer structures havingouter tube sections with large diameters.

FIG. 14 is a bottom view of the thermally-insulated helically-finnedinner tube section shown in FIG. 13.

FIG. 15 is a cross-sectional view of the thermally-insulatedhelically-finned inner tube section shown in FIG. 14, taken along theline 15-15 thereof showing the insulated central inner tube section orsleeve (e.g. made from high density, foamed plastic) that is fusionwelded on both ends inside the helically-finned inner tube section of acoaxial-flow heat transfer structure of the present invention, so as toprovide a gas gap, filled with high pressure argon or other gas beforebeing fusion welded together.

FIG. 16 is an elevated front view of a helically-finned inner tubesection fitted with a joint collar but without a thermally-insulatedcentral tube section, for use in coaxial-flow heat transfer structureshaving outer tube sections with large diameters.

FIG. 17 is a top view of the helically-finned inner tube section shownin FIG. 16.

FIG. 18 is a cross-sectional view of the helically-finned inner tubesection shown in FIG. 16, taken along the line 18-18 thereof.

FIG. 19 is an elevated front view of a helically-finned inner tubesection fitted with a thermally-insulated central tube sectionsupporting, on its outer surface, double sets of helically-extendingfins for use in creating a double helically-extending outer flow channelbetween the inner tube section and the thermally-conductive outer tubesection of the coaxial-flow heat transfer structure of the presentinvention.

FIG. 20 is a front view of a tubing shoe structure that is fusion weldedto the bottom of the helically-finned inner tube section of thecoaxial-flow heat transfer structure of the present invention, so as toprotect the helically-extending fins during the installation process.

FIG. 21 is a top view of the helically-finned tubing shoe shown in FIG.20.

FIG. 22 is a front view of a smooth thermally-conductive outer tubesection for use in the coaxial-flow heat transfer structure of thepresent invention, wherein the outer tube section is preferably madefrom metal to provide a high heat transfer coefficient, and has threadedcollars for attaching the joints of tube sections together, and isgrouted in the Earth using thermally conductive cement to maximize

FIG. 23 is a top view of the thermally-conductive outer tube section ofFIG. 22.

FIG. 24 is a side view of the thermally-conductive outer tube section ofFIG. 26.

FIG. 25 is a front view of a fluted thermally-conductive outer tubesection for use with the coaxial-flow heat transfer structure of thepresent invention, wherein the flutes on the thermally-conductiveplastic outer tube section provide additional surface area to counteractthe low heat transfer coefficient of the plastic material, and providethe thermally-conductive plastic outer tube additional strength whengrouted in the Earth using thermally conductive cement.

FIG. 26 is a top view of the fluted thermally-conductive outer tubesection of FIG. 25, taken along line 26-26 therein.

FIG. 27 is a side view of the fluted thermally-conductive outer tubesection of FIG. 26, taken along line 27-27 therein.

FIG. 28 is a partial cross-sectional view of a coaxial-flow heattransfer structure of the present invention employing a singlehelically-finned inner tube section installed within a thermallyconductive outer tube section, and shown being operated in its forwardflow direction, wherein a heat exchanging fluid is pumped through itsinput port and down the inner flow channel of the inner tube section,where upon reaching the bottom of the inner tube section, the fluidreverses its direction at the distal portion of the coaxial-flow heattransfer structure, and then flows along the helically-extending outerflow channel and out the output port at the proximal end.

FIG. 29 is a partial cross-sectional view of a coaxial-flow heattransfer structure of the present invention employing a singlehelically-finned inner tube section installed within a thermallyconductive outer tube section, shown operated in its reverse flowdirection, wherein a heat exchanging fluid is pumped through its inputport and down the outer helical flow channel between the outer and innertube sections, where upon it reverses direction at the distal portion ofthe coaxial-flow heat transfer structure, and then flows along the innerflow channel and out the output port at the proximal end.

FIG. 30 is a partial cross-sectional view of a coaxial-flow heattransfer structure of the present invention employing a doublehelically-finned inner tube section installed within a thermallyconductive outer tube section, shown operated in its forward flowdirection, wherein a heat exchanging fluid is pumped through the inputport and down the inner flow channel of the inner tube section, whereupon it reverses direction at the distal portion of the coaxial-flowheat transfer structure, and then flows along the outer helical flowchannel and out the output port at the proximal end.

FIG. 31 is a front, partially cross-sectional view of a coaxial-flowheat transfer structure of the present invention having a flutedthermally-conductive outer tube section with a single helically finnedinner tube section installed therein so as to provide ahelically-extending outer flow channel that corresponds with the flutedsurfaces along the outer tube section.

FIG. 32 is a cross-sectional view of the coaxial-flow heat transferstructure of the present invention, taken along line 32-32 in FIG. 31.

FIG. 33 is a front, partially cross-sectional view of a coaxial-flowheat transfer structure of FIGS. 31 and 32, showing the helical flowpattern of heat exchanging fluid as it is pumped down thehelically-extending outer flow channel and flows up thecoaxially-arranged inner flow channel of the coaxial-flow structure.

FIG. 34 is a front, partially cross-sectional view of the coaxial-flowheat transfer structure of FIGS. 31 and 32, showing the helical flowpattern of heat exchanging fluid as it is pumped down the inner flowchannel and flows up the coaxially-arranged helically-extending outerflow channel of the coaxial-flow structure.

FIG. 35 is a schematic representation of a heat transfer systemcomprising conventional heat transfer equipment in collaboration atleast one coaxial-flow heat transfer structure of the present invention,as generally depicted in FIG. 2.

FIG. 36 is an enlarged view of a section of the helically-extendingouter flow channel provided in the coaxial-flow heat transfer structureof FIG. 35, showing that the cross-sectional dimensions of the outerflow channel can be selected/designed to produce fluid flows therealonghaving optimal vortex characteristics that optimize heat transferbetween the fluid within the outer flow channel and the surface of thethermally-conductive outer tube section.

FIG. 37 is a schematic representation of the cross-section of the outerflow channel identified in FIG. 36, wherein when the ratio of the sidesof the outer flow channel cross-section approaches 1/1.1 (i.e.indicative of a square-like flow control volume), the resulting fluidflow through the outer flow channel will typically have one vortex forflow rates of interest.

FIG. 38 is a schematic representation of the cross-section of the outerflow channel identified in FIG. 36, wherein when the ratio of the sidesof the outer flow channel cross-section approaches 1/2.5 (i.e.indicative of a rectangular-like flow control volume), the resultingfluid flow through the outer flow channel will typically have twovortices for flow rates of interest.

FIG. 39 is a schematic representation of the cross-section of the outerflow channel identified in FIG. 36, wherein when the ratio of the sidesof the outer flow channel cross-section approaches 1/4.0 (i.e.indicative of a rectangular-like flow control volume), the resultingfluid flow through the outer flow channel will typically have twovortices (one near each helical fin) with a laminar slot flow region inthe center region, for flow rates of interest.

FIG. 40 is a perspective partially cross-sectional view of coaxial-flowheat transfer structure of the present invention illustrated in FIG. 37,when the aspect ratio of the sides of the outer flow channelcross-section approaches 1/1.1 (i.e. indicative of a square-like flowcontrol volume), and the resulting fluid flow through thehelically-extending outer flow channel will typically have a singlevortex (i.e. rotational flow) for flow rates of interest.

FIG. 41 is a perspective partially cross-sectional view of coaxial-flowheat transfer structure of the present invention illustrated in FIG. 38,wherein when the aspect ratio of the sides of the outer flow channelcross-section approaches 1/2.25 (i.e. indicative of a rectangular-likecontrol volume), the resulting fluid flow through thehelically-extending outer flow channel will typically have two vorticesfor flow rates of interest.

FIG. 42 is a perspective partially cross-sectional view of coaxial-flowheat transfer structure of the present invention illustrated in FIG. 39,wherein when the aspect ratio of the sides of the outer flow channelcross-section approaches 1/4.0 (i.e. indicative of a rectangular-likeflow control volume), the resulting fluid flow through thehelically-extending outer flow channel will typically have two vortices(one near each helical fin) with a laminar flow region in the centerregion, for flow rates of interest.

FIG. 43 is a front, partially cross-section view of a coaxial-flow heattransfer structure of the present invention, having a corrugatedthermally-conductive outer tube section and a single helically-finnedinner tube section, producing a helically extending outer flow channelalong which turbulence is produced in the heat exchanging fluid flowingtherealong.

FIG. 44 is a side, partially cross-sectional view of a coaxial-flow heatexchanging structure, graphically illustrating the fluid distributionfrom a piped manifold around the helically extending annular outer flowchannel of the coaxial-flow heat exchanging structure, as well as aroundthe end of the inner tube section at the distal portion of thestructure.

FIG. 45 is a side, partially cross-sectional view of a coaxial-flow heatexchanging structure of the present invention installed in a well borein the Earth, showing locations of holes punched or threaded into amanifold cap installed at the proximal end, and to securely hold thehelically-finned inner tube section away from and off the bottom of thethermally-conductive outer tube that has been grouted into the Earthwith thermally-conductive cement and provide field installed pipeconnection to the manifold cap shown.

FIG. 46 is a top view of coaxial-flow heat exchanging structure shown inFIG. 45, with the fluid return and injection manifold removed forclarity, and showing the use of several small holes formed in the capportion to achieve a low friction-created pressure drop, oralternatively, the use of a single medium size hole for a higherfriction-created pressure drop.

FIG. 47 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure shown in FIG. 45, with the fluid return andinjection manifold removed for clarity of illustration, showing acompression-ring type cap welded onto the proximal end of thecoaxial-flow heat exchanging structure of the present invention, whereinthe cap employs an O-ring or U-ring seal around the proximal portion ofthe outer tube section to prevent fluid leaks.

FIG. 48 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure shown in FIG. 49, with the fluid return andinjection manifold removed for clarity of illustration, showing aclamped-type cap installed on the coaxial-flow heat exchanging structureof the present invention, wherein the cap has an O-ring or U-ring sealaround the proximal portion of the thermally-conductive outer tubesection to prevent fluid leaks.

FIG. 49 is a top view of the coaxial-flow heat exchanging structureshown in FIG. 48, taken along line 49-49 in FIG. 48.

FIG. 50 is a side view of the structure shown in FIG. 44 showing theinjection manifold field installed from commonly acquired pipingmaterial and fittings.

FIG. 51 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure of the present invention ideal for use inconcrete piling or pier installations, wherein a pair of tube fittingsare welded or fused to the side of the thermally-conductive outer tubesection, for the injection and returning heat exchanging fluids to theinner and outer flow channels realized therein.

FIG. 52 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure of the present invention ideal for use inconcrete piling or pier installations, wherein a pair of tube fittingsare welded or fused to a welded or clamped cap for the injection andreturning heat exchanging fluids to the inner and outer flow channelsrealized therein.

FIG. 53 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure of the present invention shown installed in adeviated well bore in the Earth, wherein the horizontal section of thestructure is drilled into an aquifer zone and the vertical sectionthereof connects the horizontal section back to the Earth's surface.

FIG. 54 is a side view of the coaxial-flow heat exchanging structure ofthe present invention shown installed in a vertical well bore in theEarth, for the purpose of distributing heat into the Earth from theoperation of a natural gas dehydration system connected thereto.

FIG. 55 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure of the present invention shown installed in anear horizontally-bored well in the side of a mountain, mesa, or hill,wherein the well bore path is deviated to follow an aquifer zone ifavailable at the site, and wherein, for buildings with a deep basementor built on the side of a hill, the deviated well bores are drilled inthe wall of the basement.

FIG. 56 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure of the present invention shown suspendedvertically in an aqueous solution, Earth, chemical solution or mud.

FIG. 57 is a side, partially cross-sectional view of a coaxial-flow heatexchanging structure of the present invention that is ideal for use infoundation installations, wherein the tube fittings are in a state ofcompression, and wherein a tube fitting is welded to the side of thethermally-conductive outer tube section for returning the heatexchanging fluid to the external system.

FIG. 58 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure of the present invention shown installedvertically in foundations or pilings of a bridge pier or like structure.

FIG. 59 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure of the present invention shown suspendedvertically in an aqueous solution or mud, wherein radially-extendingmetal heat exchanging fins are provided on the outer tube section toincrease the heat transfer area thereof, thereby making the circulationof aqueous solution thereabout function as an external thermo-siphon.

FIG. 60 is a side, partially cross-sectional view of the coaxial-flowheat exchanging structure of the present invention as shown in FIGS. 59showing how the fins run along the exterior surface of the outer tube.

FIG. 61 shows the coaxial-flow heat exchanging structure of the presentinvention installed in a bridge component or piling, wherein inearthquake areas, the pilings are wrapped in a metal sheath to preventstructural damage in the earthquake, and helically-extending outer flowchannels provide a ground/water source heat to prevent icing of the roadway or sidewalks during the winter season.

FIG. 62 shows the coaxial-flow heat exchanging structure of the presentinvention installed in a bridge component or piling, wherein inearthquake areas, the pilings are wrapped in a metal sheath to preventstructural damage in the earthquake, and helically extending outer flowchannels provide a ground/water source heat to prevent icing of the roadway or sidewalks during the winter.

FIG. 63 shows the coaxial-flow heat exchanging structure of the presentinvention installed in a bridge component or piling, wherein inearthquake areas, the pilings are wrapped in a metal sheath to preventstructural damage in the earthquake, and the helically-extending outerflow channels provide a ground/water source of heat energy to preventicing of the road way or sidewalks during the winter season.

FIG. 64 is a schematic representation of a first application of a singlecoaxial-flow heat exchanging structure of the present inventioninstalled within the Earth about a residential home.

FIG. 65 is a schematic representation of a first application of a singlecoaxial-flow heat exchanging structure of the present inventioninstalled within the Earth about a residential home, wherein an optionalthermal bank tank is provided for night-time operation when theelectrical energy costs are less, or for daytime operation when solarcells can provide electrical energy to the home.

FIG. 66 is a schematic representation of a first application of a threecoaxial-flow heat exchanging structure of the present inventioninstalled within the Earth about a residential home.

FIG. 67 schematically illustrates a second application where ninedeviated wells are pad drilled in order to minimize the ground surfaceimpact, reducing heat loss from horizontal gathering piping and reducingrisk of accidental damage from contractor digging operations, whereinlong term operation allows the ground loop to thermally bank heat fromthe cooling season for use in the winter season, and for cooling loadsonly, a shallow horizontal loop can be added to the ground-loop toremove heat from the thermal bank during the winter season.

FIG. 68 illustrates the application shown in FIG. 67, taken along line68-68 in FIG. 68.

FIG. 69 is a schematic representation of a system comprising elevendeviated wells, in which each coaxial-flow heat exchanger of the presentinvention is installed in thermally-conductive cement, and connectedtogether using piping so as to form a heat pumping network.

FIG. 70 is a schematic representation of a first application using seawater as the heat-pump heat sink for gas dehydration and oil de-waxing,wherein one or more coaxial-flow heat exchanging structures of thepresent invention are installed in the ocean above the ocean floor, forthe purpose of extracting heat from the gas so as to cause thetemperature thereof to drop, thereby condensing water vapor and/or lighthydrocarbon vapors in the gas stream.

FIG. 71 is a schematic representation of a second application usingballast water as the heat-pump heat sink for gas dehydration and oilde-waxing, wherein one or more coaxial-flow heat exchanging structuresof the present invention are installed in the ocean above the oceanfloor, for the purpose of extracting heat from the gas so as to causethe temperature thereof to drop, thereby condensing water vapor and/orlight hydrocarbon vapors in the gas stream.

FIG. 72 is a schematic representation of a third application usingballast water as the heat-pump heat sink for gas dehydration and oilde-waxing, wherein one or more coaxial-flow heat exchanging structuresof the present invention are installed below the ocean floor, for thepurpose of extracting heat from the gas so as to cause the temperaturethereof to drop, thereby condensing water vapor and/or light hydrocarbonvapors in the gas stream.

FIG. 73 is a schematic representation of an application of thecoaxial-flow heat exchanging structure of the present invention employedin a ground-loop heat exchanging system, designed for dehydrating, onshore, pipeline-quality gas produced from remote off shore wells.

FIG. 74 is a schematic representation of an application of a number ofcoaxial-flow heat exchanging structures of the present invention shownsuspended in sea water, buried beneath the mud line on the ocean floor,and used as a heat exchanger in the evaporative section of the liquidnatural gas gasification process equipment, designed for gasifyingliquid natural gas for storage and distribution.

FIG. 75 is a schematic representation of a permanent or skid mountednatural gas dehydration system, also shown in FIG. 73, wherein the gasin the liquid separator is cooled to a temperature near the aquifertemperature, the gas is then cooled using a refrigeration system to atemperature near the gas hydrate temperature, and wherein a glycol cycleor calcium chloride salt cycle is used to remove moisture from thegas-hydrate temperature to the -30 F dew point for pipeline sales, andwherein the system reduces the energy costs of gas dehydration andeliminates the release of benzene, toluene and other carcinogenetichydrocarbon vapors to the atmosphere.

FIG. 76 is a schematic representation of a submarine employing thecoaxial-flow heat exchanging structure of the present inventioninstalled within a seawater heat exchanging subsystem for centralizedair conditioning and equipment cooling.

FIG. 77 is a schematic representation of a submarine employing thecoaxial-flow heat exchanging structure of the present inventioninstalled within a seawater heat exchanging subsystem for decentralizedair conditioning and equipment cooling.

FIG. 78 is a side, partially cross-sectional view of a coaxial-flow heatexchange structure of the present invention constructed having finsabout the outer tube exterior to be used as a component of a heatexchanging refrigeration condenser, refrigeration evaporator (coolingcoil), heat pump heating and cooling coil, combustion engine radiator,and a component of other air or liquid heat exchangers having a fluiddirection of flow as shown.

FIG. 79 is a side, partially cross-sectional view of a coaxial-flow heatexchange structure of the present invention constructed having finsabout the exterior of the outer tube section to be used as a componentof a heat exchanging refrigeration condenser, refrigeration evaporator(cooling coil), heat pump heating and cooling coil, combustion engineradiator, and/or a component of other air or liquid heat exchangershaving a fluid flow direction as shown.

FIG. 80 is a side, partially cross-sectional view of a plurality ofcoaxial-flow heat exchangers of the present invention, shown used in asubmarine application and other air conditioning applications, whereinthe outer tube sections are made of metal and are finned so as toprovide maximum heat transfer with the ambient environment.

FIG. 81 is a first side view of the plurality of coaxial-flow heatexchangers shown in FIG. 80, taken along line 81-81 therein.

FIG. 82 is a second side view of the plurality of coaxial-flow heatexchangers shown in FIG. 80, taken along line 82-82 therein.

FIG. 83 is a front view of a plurality of coaxial-flow heat exchangingstructure of the present invention installed in a pressure vessel usedas an aqueous-based fluid-to-fluid, fluid to air, and/or refrigerationevaporator (chiller) or condensing heat exchanger (tube and shell heatexchanger).

FIG. 84 is a right side view of a coaxial-flow heat exchanging structureof the present invention shown in FIG. 83.

FIG. 85 is a front view of a plurality of coaxial-flow heat exchangingstructures of the present invention shown used as an aqueous-based,fluid to air, refrigeration evaporator (chiller) or heat pump condensingheat exchanger.

FIG. 86 is a side partially cross-sectional view of the aqueous-basedfluid, and refrigerant evaporation based, fluid to air heat exchangershown in FIG. 85, taken along line 86-86 therein. wherein the outertubes are made of metal and are finned so as to provide maximum heattransfer with the ambient environment, which can be made of plasticcontaining heat transfer enhancing additives.

FIG. 87 is a rear view of the aqueous-based fluid, and refrigerantevaporation based, fluid to air heat exchanger shown in FIG. 86, takenalong line 87-87 therein.

FIG. 88 is a schematic representation of a first application of acoaxial-flow heat exchanging structure of the present inventioninstalled on the outlet of a furnace connected to an outdoor compressorbased condensing unit or heat pump, and functioning as a refrigerationcooling coil or heat pump heating and cooling coil

FIG. 89 is a schematic representation of the segmented helically-finnedinner tube section, with integrated mixing zones, for installation inthe outer tube sections of a coaxial-flow heat exchanging structure asshown in FIG. 90.

FIG. 90 is a cross-sectional view of the segmented helically finnedinner tube section, with integrated mixing zones, installed in the outertube sections of a coaxial-flow heat exchanging structure.

FIG. 91 is a schematic representation of a coaxial-flow heat exchangingstructure as shown in FIG. 90, wherein its segmented helically-finnedinner tube sections, with fluid mixing zones formed therebetween, arerealized using tube segments made of extruded pieces that are joinedtogether by plastic couplings that are glued or welded together.

FIG. 92 is a schematic representation of a segment of a coaxial-flowheat exchanging structure, wherein it has one segmented helically-finnedinner tube section on one end, and one fluid mixing zone formed on theopposite end, wherein the extruded pieces are joined together by plasticcouplings that are glued or welded together.

FIG. 93 is a schematic representation of a wrap-around type single finsegment that can be applied about a section of flexible or rigid (inner)tubing so as to realize the helically-finned inner tube sectionsemployed in the coaxial-flow heat exchanging structure of FIG. 96.

FIG. 94 is a schematic representation of a wrap-around type single finsegment shown as it would appear wrapped in one direction about asection of flexible or rigid (inner) tubing so as to realize thehelically-finned inner tube sections employed in the coaxial-flow heatexchanging structure of FIG. 96.

FIG. 95 is a schematic representation of a wrap-around type single finsegment shown as it would appear wrapped in the opposite direction asshown in FIG. 95 about a section of flexible or rigid (inner) tubing soas to realize the helically-finned inner tube sections employed in thecoaxial-flow heat exchanging structure of FIG. 96.

FIG. 96 is a schematic cross-sectional view of the segmentedhelically-finned inner tube section shown installed withinthermally-conductive outer tube sections of the coaxial-flow heatexchanging structure, so that a mixing zone is provided for turbulentlymixing the heat exchanging fluid flowing along the helically-extendingouter flow channel, to break up boundary layers that may form on thewall surfaces of the outer flow channel, thereby increasing theefficiency of the system to exchange heat energy with the ambientenvironment.

FIG. 97 is a cross-sectional view of an alternative illustrativeembodiment of the coaxial-flow heat exchanging structure of the presentinvention, wherein a segmented, helically-extending finned inner tubesections having alternating left and righted handed twists are installedwithin thermally-conductive outer tube sections of the coaxial-flow heatexchanging structure, so that a mixing zone is provided for turbulentlymixing the heat exchanging fluid flowing along the helically-extendingouter flow channel, to break up boundary layers that may form on theouter channel wall surfaces, and thereby increasing the efficiency ofthe system to exchange heat energy with the ambient environment.

FIG. 98 is a perspective view of the wrap-around single fin segment withits integrated base layer that has been extruded flat and parallel whileheated to its plastic point, wherein the segment can be wrapped around amandrel so as to provide the fin with a helical pitch to match thetubing or hose size to be employed within a coaxial-flow heat exchangingstructure as shown in FIG. 90.

FIG. 99 is a side view of a wrap-around single fin segment having a lefthand twist—in comparison with a right hand twist—provided to thewrap-around fin segment shown in FIG. 98.

FIG. 100 is a schematic representation of a segmented helically-finnedinner tube section employed in the coaxial-flow heat transfer structureof FIG. 90.

FIG. 101 is a plan view of a molded or extruded multiple-finned segment,shown prior to configuration about inner tube sections installed withina coaxial-flow heat exchanging structure as shown in FIG. 102.

FIG. 102 is a side partial cross-sectional view of the coaxial-flow heatexchanging structure of the present invention constructed from singlefin segments installed on one or more inner tube sections containedwithin the outer tube (i.e. outer casing), and provided with a re-mixingzone between helical fin segments for the turbulent mixing of heatexchanging fluid along the helically extending outer flow channel.

FIG. 103 is a side, partial cross-sectional view of the coaxial-flowheat exchanging structure of the present invention employing segmentedsingle fin segments, having alternating left and righted handed twists,installed on a inner tube sections contained within the outer tubesections of the structure, and providing a re-mixing zone betweenhelical fin segments for the turbulent mixing of heat exchanging fluidalong the helically-extending outer flow channel.

FIG. 104 is a schematic representation of a machine designed toautomatically attach single or multi-finned segments onto the outersurface of flexible tubing as the tubing is being rolled off a supportspool, and for the assembled finned tubing structure to then be rolledup onto a storage spool for subsequent transport to a site wherecoaxial-flow heat transfer structures are to be constructed inaccordance with the present invention.

FIG. 105 is a schematic representation of a ground-supported spool ofmulti-finned heat exchanging segments for use in constructingcoaxial-flow heat transfer structures according to the presentinvention, wherein the spool of segments are shown being loaded into anouter tube section (i.e. casing) that has been installed within a wellbore filled with thermally-conductive cement.

FIG. 106 is a cross-sectional view of a well head illustrating howcommonly found metallic or plastic fittings can be used to connectpiping used to direct the heat transfer fluid to and from heating,cooling or other heat transfer circulating devices and equipment inconnection with an arrangement of coaxial-flow heat exchangingstructures of the present invention.

FIG. 107 is a perspective partially cross-sectional view of acoaxial-flow heat exchanging structure of the present invention, whereina plurality of rows of zig-zaging fluid turbulencegenerators/projections are provided as segments on the outer surface ofthe inner tube section for the purpose of generating turbulence in theheat exchanging fluid flowing through the outer flow channel.

FIG. 108 is an elevated side view of the plurality of fluid turbulencegenerators/projections provided on the outer surface of the inner tubesection of the coaxial-flow heat exchanging structure of FIG. 107.

FIG. 109 is a cross-sectional view of the inner tube section of thecoaxial-flow heat exchanger, taken along line D-D shown in FIG. 108.

FIG. 110 is a partially transparent perspective view of a coaxial-flowheat exchanging structure of the present invention, wherein the innertube section and its plurality of helically extending fins are formed byan extrusion process, and subsequently inserted within the outer tubesection to form the helically-extending flow channels between the innerand outer tube sections.

FIG. 111 is an elevated side view of a coaxial-flow heat exchangingstructure of the present invention, wherein the outer tube section,inner tube section and helically-extending fins are formed as a unitaryproduct using a plastic extrusion process.

FIG. 112 is a perspective view of the coaxial-flow heat exchangingstructure of FIG. 111.

FIG. 113 is a cross-sectional view of the coaxial-flow heat exchangingstructure of FIG. 112, taken along line B-B therein.

FIG. 114 is a perspective, partially cutaway view of a coaxial-flow heatexchanging structure of another embodiment of the present invention,wherein the inner tube section has multiple rows of discrete finsegments helically-extending along the outer flow channel between theinner and outer tube sections, and formable as flexible planar segments(through modeling techniques) and then applied about the outer surfaceof the inner tube structure.

FIG. 115 is a perspective, partially cutaway view of a coaxial-flow heatexchanging structure of another embodiment of the present invention,employing a continuous helically-extending turbulence generatingstructure along the outer flow channel between the inner and outer tubesections.

FIG. 116 is a perspective view of a single helically-finned turbulencegenerating structure having a solid shaft, designed for insertion withinconventional tubing for the purpose of generating flow turbulence alongthe flow channel thereof, and increase heat transfer through the tubewalls.

FIG. 117 is a perspective view of a conventional U-tube ground loop, asshown in FIGS. 1B and 1C, with the helically-finned turbulencegenerating structure of FIG. 116 installed within the flow channelthereof for the purposes of improving heat transfer efficiency to theambient environment.

FIG. 118 is a schematic diagram of an air conditioning system employinga system of ground loop heat transferring wells employing coaxial-flowheat transfer structures of the present invention therein, functioningas a heat transfer sub-system connected to a water-cooled ground sourcecondensing unit found on a typical air conditioning system, where anelectric or gas fired furnace is used during the heating mode ofoperation.

FIG. 119 is a schematic diagram of an air conditioning system employinga system of ground loop heat transferring wells employing coaxial-flowheat transfer structures of the present invention therein, functioningas a heat transfer sub-system connected to a water-to-water airconditioning heat pump.

FIG. 120 is a schematic representation of a RF (or microwave)transmission/reception tower and accompanying base station housing (i.e.shelter) sensitive electronic equipment within an environment that isthermally controlled by a system employing a plurality of coaxial-flowheat exchanging structures of the present invention installed in aplurality of vertical well bores, using thermally conductive cement.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENTINVENTION

Referring to the figures in the accompanying Drawings, the variousillustrative embodiments of the coaxial-flow heat exchanging (i.e.transferring) structure of the present invention will be described ingreat detail, wherein like elements will be indicated using likereference numerals.

As shown in FIG. 2, the present invention relates to a coaxial-flow typeheat transfer structure 1 for installation in an ambient environment 8for facilitating the transfer of heat energy between an external heatenergy producing system 11, 12, and 13, and the ambient environment. Asshown in the illustrative embodiment of FIG. 2, the coaxial-flow typeheat transfer structure 1 comprises: a proximal end 7, and a distal end5; an input port 9, provided at the proximal end, for receiving a heat(energy) transferring fluid at a first temperature from an external heatenergy producing system 11, 12 and 13; an output port 10, provided atthe proximal end, for outputting the heat transferring fluid at a secondtemperature to the heat energy producing system; an inner tube section 2having an outer wall surface extending between the proximal and distalends, and supporting an inner flow channel 6 having a substantiallyuniform inner diameter along its entire length, and into which the heatexchanging fluid can be introduced from the input port, and along whichthe heat exchanging fluid can flow in a substantially laminar mannertowards the distal end; an outer tube section 4, disposed coaxiallyaround the inner tube section 2, and having an inner wall surfaceextending between the proximal and distal ends, and the outer tubesection being in thermal communication with the ambient environment.

As shown in FIG. 2, an outer flow channel 6B of annulus geometry isprovided between the outer wall surface of the inner tube section andthe inner wall surface of the outer tube section, and capable ofconducting heat exchanging fluid from the distal extend, along the outerflow channel 6B towards the proximal end, and exiting from the outputport 10. A turbulence generating structure (e.g. a helically-arrangedfin structure) is disposed along a substantial portion of the length ofthe outer flow channel 6B so as to introduce turbulence into the flow ofthe heat exchanging fluid flowing along the outer flow channel, from thedistal end towards the proximal end, and thereby improving the transferof heat energy between the heat exchanging fluid and the ambientenvironment along the length of the outer flow channel 6B.

In FIGS. 3 and 4, reference numeral 3 indicates the turbulence generatorrealized as a single helically-extending fin structure projecting fromthe surface of the inner tube section 2. The helically-extending finstructure 3 can be made out of plastic or metal depending on the staticload on the fin 3. The outer wall of the helically-finned inner tubesection 2 can be made out of metal or plastic depending on the crush,buckling or tensile load of the tubing laying or hanging in the wellbore.

As shown in FIGS. 3 and 4, a single helically-finned 3 insulated innertube section 2 is used to create a helically-extending outer flowchannel 6B within the coaxial-flow heat exchanging structure of thepresent invention. As shown, this small-diameter, helically-finned innertubing can be delivered rolled on a large spool to install in thethermally-conductive outer tube section 4 of the system, and thehelically-finned inner tubing can be cut to size and the well capstructure fused on as shown in FIG. 106.

FIG. 5 shows the front view of double helically-finned inner tubesection. Reference numeral 2 points to the insulated helically-finnedinner tube section. Reference numeral 3indicates the firsthelically-indicating fin structure while 3A points to the secondhelically-extending fin structure. The number of helically-extending finstructures (e.g. turbulence generating structures) used in anyparticular application is determined by the cross-sectional shape of theouter flow channel and this topic is discussed in detail with referenceto FIGS. 35 through 42.

The linear, leading and trailing edges of a number of the multipleangular fins can be angular or filleted. As shown in FIG. 5 and 30, adouble helically-extending fin set is shown used to create helical fluidflow along the helically-extending outer flow channels of between theinner and outer tube sections. In this design, the friction pressuredrop in the ground loop can be reduced, and the number of fin sets canbe increased to reduce the flow path length in the well bore. Also, asthe diameter of the thermally-conductive outer tube increases, thenumber of helically-extending fins can be increased to keep the aspectratio of the outer flow channel shape close to 2 to 1, as shown in FIGS.35 through 42.

In FIGS. 6 and 7, a single thermally-insulated helically-finned innertubing section is shown for installation in the thermally-conductiveouter tube section 4 of FIG. 2. In this inner tube section design, a gasgap 17 is formed between a central insulated inner tube 14 and thehelically-finned inner tube 2, which provides thermal insulation betweenthe inner and outer flow channels. The gap distance between the wallsremains uniform due to the three standoffs 18, 19 and 20 provided on thecentral insulation tube. Reference numeral 14 indicates the wallthickness of the center tube in helically-finned inner tubing section.In the illustrative embodiment, the wall thickness of the center tube iscalculated using the following factors: the material strength; thebuckling load of setting the inner tubing down on thethermally-conductive tube shoe, shown in FIG. 20; the tensile load ofsupporting the inner tubing from the thermally-conductive outer tubecap, and the crush pressure rating of the tube.

In FIG. 6, reference numeral 15 indicates the inner flow channel. Thediameter of the inner flow channel is determined from the amount ofthermal storage required in the ground loop, or from the frictionpressure drop. Reference numeral 2 indicates the wall thickness of thehelically-finned inner tube section which must support the tensile loadof the tubing and turbulence generators 3 (i.e. helical fins) hangingfrom the cap component of the thermally-conductive outer tube and itmust support the shear stress of installing the inner tubing in thethermally-conductive outer tube 4. The surface of the fins 3 should besmooth to reduce the pressure drop created by surface friction on theflowing fluid. Reference numerals 18, 19 and 20 indicate the stand offson the center tube used to create the static or dead gas space 17between the center tube and the helically-finned inner tube section. Thestandoffs can have a triangular shape for installation at the factory,or a half cylinder shape for center tube installation in the field. Thenumber of standoffs used is determined by the center tube diameter andcenter tube material. When used for insulating the inner tube inside theassembly shown in FIG. 115, the center tube 14 can be extruded as awhole assembly with standoffs 18, 19 and 20 integrated therewith.

For fin structures having small outside diameters, the edge can be flat,but for fin structures having large diameters, the edge should be radiusto prevent fin damage caused by hanging up on an edge in thethermally-conductive outer tube section. The static or dead gas space 17can also be filled with a ceramic fiber, ceramic paper, or othersuitable insulating material. The gas space can be pressurized with aninert, non-condensable gas such as argon, nitrogen, refrigerant gases,methane, or ethane. The charge gas pressure should be equivalent to halfthe hydrostatic pressure in the well bore. Reference numeral 16indicates the interior surface of the outer helically-finned inner tubesection. The surface should be smooth to reduce friction pressure lossand could be curved to promote tangential rotation of the circulatedheat exchanging fluid. To reduce the heat transfer between the centertube and outer tube, the surface could be coated with a reflective metalsuch as aluminum, silver or gold or coated with a reflective ceramicpowder such as titanium dioxide.

In FIGS. 8 and 9, the single helically-finned inner tubing section ofFIGS. 6 and 7 is shown without the inner/central insulation tubeinstalled. In this design, the fins 3 can be extruded with the tubingfor small diameters or extruded over a larger diameter tube section. Fordiameters exceeding 18 inches or 0.5 meters, the fins can be rolled fromflat stock and welded on the tubing section. Reference numeral 18indicates the inner diameter of the helically-finned inner tube sectionwhere in the center tube will be assembled. Reference numeral 19indicates the exterior diameter of the helically-finned inner tubesection. While not shown in these figures, both the top and bottomsurfaces of the helical fin 3 can be curved to promote tangentialrotation of the fluid and to prevent slow flowing areas in the cornersof the helical outer flow channel.

As shown in FIG. 10, reference 18 indicates the interior surface of thehelically-finned inner tube section 2. This surface could be coated witha reflective metal such as aluminum, silver or gold or coated with areflective ceramic powder such as titanium dioxide. Reference numeral 19indicates the exterior surface of the helically-finned inner tubesection. This surface should be smooth to reduce the friction pressureof the circulating fluid. The surface could also be fluted to promotethe tangential rotation of the circulating fluid. Reference numeral 20shows the start of the clock-wise rotation of the helical fin structure3 and numeral 1 shows the start of the clock-wise rotation of thehelical fin structure 3A.

For fins having small outside diameters, the edge should be flat toincrease the friction pressure drop of the slot flow so the circulatingfluid follows (or is guided by) the helically-extending fins instead oftrying to bypass it. But for large diameters, the edge should be radiuswith additional thickness to prevent helically-extending fin damage byhanging up on an edge in thermally-conductive outer tube collar. Thedifference in thickness between reference numerals 18 and 19 indicatesthe wall thickness of the helically-finned inner tube section. The wallthickness is determined by the material used and the compressive,tensile and shears loads the tubing wall will be exposed to duringinstallation and operation.

As shown in FIGS. 11 and 12, the standoffs 22, 23 and 24 on the centraltubing provide the gas gap needed for insulation between the centralinsulation tube 14 inside surface 26 and helically-finned inner tube,wherein the fill gas can be argon, nitrogen, or even ethane. In thisdesign, a vacuum is established in the field to check for leaks, thenthe gap is filled with gas to half of the bottom hole (well) pressure.Notably, the standoffs shown in FIG. 12 have a cross-sectional roundedshape instead of the triangular shape, for easier installation in thefield and to prevent damage to the edge of the standoffs duringinstallation in the field. Reference numeral 26 indicates the insidesurface of the central tube where a heat transfer fluid can pass throughthe center 15.

In FIGS. 13, 14 and 15, thermally-insulated helically-finned innertubing is joined with a collar 28 for large diameter helically-finnedtubing that cannot be rolled on spool. In this application, the collarcan be fusion welded or threaded on the inside surface 29 to the nextjoint in the field to make a continuous piece of tubing for installationin the thermally-conductive outer tube providing fluid flow through theinner flow channel 6A to the distal end of the structure. Preferably,the central tube 14 is fuse welded at the factory on both ends 30 and 31of the inner tube to provide the seal for the gas gap between these twotube sections, to allow charging with gas at the factory.

FIGS. 16, 17, and 18 show a helically-finned inner tubing section 2 thathas a (joining) collar 28 but not a central insulating tube installed.In this application, the collar is usually threaded for metal innertubing sections, slip for short lengths of plastic tubing, or evenprovide with a twisted lock with O-ring seal for long lengths of plastictubing. Preferably, the wire coil in the collar can be used to fusionweld plastic tubing in the field during installation.

In FIGS. 19, illustrates how the structure in FIG. 5 can be extrudedwith a (oining) collar as shown FIG. 16.

FIGS. 20 and 21 show a shoe structure (i.e. fin protection structure).This structure can be fusion welded at points on surface 32 to thebottom (i.e. distal) end of the helically-finned inner tubing section.The shoe has a number of protectors 33, 34, 35 and 36 having a widerradial distance (from the shoe center) than the outer diameter of thehelically-finned inner tubing outer diameter so as to provide a way ofand means for protecting the helical fins during the installationprocess.

In FIGS. 22, 23 and 24, a smooth thermally-conductive outer tubesection, sealed at the distal end 5 with a cap structure 37, is shownfrom various views. During the installation process, this outer tubestructure 4 is grouted in the Earth using thermally-conductive cement.Preferably, the smooth thermally-conductive outer tube is constructedfrom metal to ensure that it has a high heat transfer coefficient. Inthe illustrative embodiment, the collars, threaded, thermally fused, andspecialty adhesives, are used to attach the outer tube sectionstogether, and the thermally-conductive outer tube shoe shown in FIG. 20can contain a cement valve and a plug catcher. Small diameter tubing isused inside the thermally-conductive outer tube 4 to prevent groutcontamination therewithin and to flush the mud out of the outer tubeafter grout placement. Such precautions should be taken because hardenedgrout inside the outer tube can damage the plastic helical edges duringinsulation as well as reduce the heat transfer coefficient of the metalwall. One such precaution involves placing a small diameter coiledtubing in the annulus space between the well bore and the outer surfaceof the outer tube section, and pumping through this coiled tubing tofill the annulus at substantially the same rate as the coiled tubing ispulled our of the annulus to the Earth's surface. A quantity of groutingmaterial should be left to set up at the bottom of the hole to hold theouter tube in place during the rest of the grouting procedure. Water canbe added inside the outer tubing 4 giving it weight, guarding againstexcessive buoyancy and possible crushing which can occur during thegrouting procedure before the grout has time to solidify.

In FIGS. 25, 26 and 27, a fluted thermally-conductive outer tube section4A is shown. In this design, the flutes on a thermally-conductive outertube provides additional surface area to counteract the low heattransfer coefficient of the plastic. The flutes also provide thethermally-conductive outer tube with additional strength. If the desiredthermally-conductive outer tubing material has sufficient burst pressurestrength. The thermally-conductive outer tube cap 5 can also have metalforks to dig into the wall of the hole to prevent thethermally-conductive outer tube from floating when the grout is pumpedto surface. An option to prevent the thermally-conductive outer tubefrom floating off the bottom of the hole is to flash set a small volumeof grout in the bottom of the hole. This will serve to hold thethermally-conductive outer tube down while the rest of the grout ispumped to the

In FIGS. 28 and 29, the forward flow pattern 15 and 38 and the reverseflow pattern 39 are illustrated in a coaxial-flow heat transferstructure having a smooth thermally-conductive outer tube section andsingle helically-finned inner tube section. During the cooling season,pumping heat exchanging fluid down the outer flow channel provides thebest approximation to a cross flow heat exchanger for liquid-gasmixtures where the liquid adsorbs the gas phase when the pressureincreases as the mixture is pumped down the thermally-conductive outerflow channel. As the gas phase is absorbed, the fluid temperatureincreases with depth, which in turn increases the heat transfer to theground or water. During heating season or winter operation, pumping acold aqueous fluid down the outer flow channel provides the bestapproximation to a cross flow heat exchanger due to the groundtemperature increasing with depth. For horizontal or deviated wells, itis better to pump the fluid down the inner flow channel to maximize heattransfer at the distal end of the well.

In FIG. 30, the forward flow pattern 15 and 41 is illustrated in acoaxial-flow heat transfer structure having a smooththermally-conductive outer tube section and inner tube section 2 havingmultiple helical fins.

FIGS. 31 and 32 show a coaxial-flow heat transfer structure having afluted thermally-conductive outer tube 4A and a single helical-fin innertube section 2, forming a single helically-extending outer flow channel.In this design, the pitch of the helical fins 3, and the flutedthermally-conductive outer tube surface, should be practically close formaintaining the helical flow pattern in the outer flow channel. Thefluid will bypass the fins around the space in the flutes. The wholeassembly can be extruded together as a tubing-thermally-conductive outertube joint combination, and the joint combination can be fusion weldedin the field with preinstalled wire coils in the collars. To grout theouter tube in a well bore, a small diameter coiled tubing is installedin the annulus of the hole, as described above. The small diametercoiling tubing is then pulled to the surface at substantially the samerate as the grout fills the annulus of the well bore. Water can be addedinside the outer tubing 4 giving it weight, guarding against excessivebuoyancy and possible crushing which can occur during the groutingprocedure before the grout has time to solidify. As shown, 48illustrates the excentric offset of the proximal end circular surface.

FIG. 33 illustrates the helical flow pattern 39 and 40 within thecoaxial-flow heat transfer structure, as the fluid is pumped down thehelically-extending outer flow channel and up inner flow channel. Fornear vertical well bores gives, pumping fluid down the outer flowchannel provides the best approximation to a cross flow heat exchangerfor ground temperatures close the surface. For a coaxial-flow heattransfer structure installed in horizontal or deviated wells inaquifers, it is better to pump fluid down the inner flow channel tomaximize the heat transfer at the distal end of the well bore.

FIG. 34 illustrates the forward flow pattern 15 and 41 for acoaxial-flow heat transfer structure having a double helically-finnedinner tube section. In this design, the multiple helical fins are usedfor large diameter thermally-conductive outer tube. For large diameters,the helically-finned tubing joints can be pre-installed in thethermally-conductive outer tube joints for shipment. O-ring seals areused in the helically-finned tube collars, so when thermally-conductiveouter tube joints are joined together, the O-ring seals thehelically-finned tubing also. This helps reduce installation cost andshipping cost for large diameter ground loops.

FIG. 35 is a schematic representation of a heat transfer systemcomprising conventional heat transfer equipment 11 in combination withleast one coaxial-flow heat transfer structure 8 of the presentinvention, as generally depicted in FIG. 2. As shown in FIG. 35, a heattransfer fluid is pumped through the mechanical heat transfer equipment11, including a heat exchanger, by a fluid pump. The heat transfer fluidtravels to the co-axial heat transfer structure 8 through pipe 9,entering the center tube of the co-axial heat transfer structure at theproximal end through input port 7 where the heat transfer fluid beginsto travel in a laminar flow profile as shown in FIGS. 1 and 1A down thelength of the inner flow channel 6A of the inner tube section 2. Thefluid then reverses its flow direction, transitioning into a turbulentflow profile as it travels toward the surface through outer flow channel6B, along which it encounters helically-extending fin structures (i.e.turbulence generators). The conditioned heat transfer fluid is thenreturned to the mechanical heat transfer equipment 11 through pipe 10for conditioning in the system and subsequent recirculation through theco-axial heat transfer structure.

FIG. 36 shows an enlarged view of a section of the helically extendingouter flow channel 6 provided for in the coaxial-flow heat transferstructure of FIG. 35. As shown, the cross-sectional dimensions of theouter flow channel 6 between the interior surface of the outer tubesection 4, the exterior surface of the inner tube section 2, and thehelical flow guide fins 2 can be selected/designed to produce fluidflows therealong having optimal vortex characteristics that optimizeheat transfer between the fluid within the outer flow channel 6 and thesurface of the thermally-conductive outer tube section 4.

FIG. 37 illustrates the rotational flow characteristics of fluid 43flowing along the outer flow channel identified in FIG. 36 when theratio of the sides of the outer flow channel cross-section (i.e. flowchannel slot ration 42) approaches 1/1.1 (i.e. indicative of asquare-like control volume). Under such geometrical conditions, theresulting fluid flow through the outer flow channel 6 will typicallyhave one vortex 43 for flow rates of interest (e.g. 25 to 35 GPM) atlower than desired velocity with a lower rate of system heat transfercapacity caused by a less affective rotational flow profile 43.

FIG. 38 illustrates the rotational flow characteristics of fluid flowingalong the outer flow channel identified in FIG. 36 when the ratio of thesides of the outer flow channel cross-section 44 approaches 1/2.5 (i.e.indicative of a rectangular-like control volume). Under such geometricalconditions, the resulting fluid flow through the outer flow channel 44will typically have two vortices 45 and 46 for flow rates of interest(e.g. 17 to 24 GPM) at optimum velocity with optimum rate of system heattransfer capacity caused by an optimum turbulent flow profile.Optimizing turbulent flow characteristics further disturbs the boundarylayer shown in FIGS. 1 and 1A, thereby increasing heat transfer intosurfaces in contact with the heat transfer fluid during fluid flow.

FIG. 39 illustrates the rotational flow characteristics of fluid flowingalong the outer flow channel identified in FIG. 36 when the ratio of thesides of the outer flow channel cross-section 47 approaches 1/4.0 (i.e.indicative of a rectangular-like control volume). Under such geometricalconditions, the resulting fluid flow through the outer flow channel 6will typically have two vortices 48 and 49 (one near each helical fin)with a laminar slot flow region in the center region, for flow rates ofinterest (e.g. 12 to 20 GPM) at higher than desired velocity with lowerrate and heat transfer capacity caused by laminar flow 4 and a smallerturbulent flow profile. The aspect ratio shown as FIG. 39 increasesrestriction to fluid flow. Increasing pressure will increase the size ofthe laminar flow 50 decreasing turbulent flow profile shown in FIG. 38.

FIG. 40 is a graphical representation of the helical flowcharacteristics of fluid 42 flowing along the outer flow channel betweenthe outside surface of inner tube section 2 and the inside surface ofouter tube section 4, identified in FIG. 37, when the aspect ratio ofthe sides of face area of the outer flow channel cross-sectionapproaches 1/2.25 (i.e. indicative of a rectangular-like controlvolume). FIG. 40 also illustrates the laminar flowing fluid 15 flowingthrough the inner tube section 2.

FIG. 41 is a graphical representation of the helical flowcharacteristics of fluid flowing along the outer flow channel betweenthe outside surface of the inner tube 2 and the inside surface of theouter tube 4, identified in FIG. 38, when the aspect ratio of the sidesof face area of the outer flow channel cross-section approaches 1/2.25(i.e. indicative of a rectangular-like control volume). FIG. 41 alsoillustrates the laminar flowing fluid 15 flowing through the inner tube2.

FIG. 42 is a graphical representation of the helical flowcharacteristics of fluid flowing along the outer flow channel 47 betweenthe outside surface of inner tube 2 and the inside surface of the outertube 4, identified in FIG. 39, when the aspect ratio of the sides offace area of the outer flow channel cross-section approaches 1/4.0 (i.e.indicative of a rectangular-like control volume). FIG. 42 alsoillustrates the laminar flowing fluid 15 flowing through the inner tube2.

FIG. 43 shows a coaxial-flow heat exchanging structure having ahelically-finned inner tube section 2 installed coaxially in acorrugated thermally-conductive outer tube 4C, between which ahelically-extending outer flow channel is formed generating turbulence45 and 46 in the heat exchanging fluid flowing therealong. A heattransfer fluid enters at 15 and passes through the inner tube 2 to theend of the inner tube where the fluid passes a shoe 32, (FIGS. 19 and20) whereupon the fluid direction of flow is reversed and redirectedinto a helical flow channel. The heat transfer fluid flow transitionsinto a turbulent flow profile along the length of the outer flowchannel. In this design, the corrugated outer tube wall 4C increases thesurface area (i.e. compared to a smooth wall pipe or tube), and strengthof the thin-walled thermally-conductive outer tube. The period of thecorrugation flutes is at least one quarter or less of the helical fin toprevent significant fluid bypass around the fins 3. While thecorrugations increase the pressure drop along the outer flow channel bya factor of about 10%, these corrugations will also increase the heattransfer rate and heat exchange surface area by a factor of about 40%.As shown an end cap 5 is welded, glued or otherwise affixed to thedistal end of the coaxial-flow structure.

FIG. 44 shows a coaxial heat transfer structure showing heat transferfluid inlet 51 and outlet 52, in which the helically-finned inner tubesection is supported in the thermally-conductive outer tube section byway of a well cap structure. As shown, the well cap holds thehelically-finned inner tube 2 off the bottom of the thermally-conductiveouter tube so as to prevent buckling of the plastic helically-finnedtubing while sealing the helically-extending outer flow channel fromfluid leaks from and into the environment. In order to prevent bucklingof the plastic helically-finned tube section, at least ⅔ of thehelically-finned tubing should be hung in tension from the well cap.Using the O-ring seal, well cap provides an easy way to remove thehelically-finned inner tubing in the even there is a fluid leak in thethermally-conductive outer tube. The well cap can be attached to thethermally-conductive outer tube section 4 by way of threads, by way ofcompression bolts, or by way of a compression ring.

In FIGS. 45 and 46, a coaxial-flow heat exchanging structure of thepresent invention is shown employing a well cap 53, at the proximal endthereof, and a shoe structure disposed at the bottom of thethermally-conductive outer tube (i.e. distal end). A O-ring seal 54 isshown sealing the cap to the outer tube 4 exterior surface. In thisapplication, a manifold structure, shown in FIG. 50 is provided forenabling fluid return and injection has been removed for purposes ofclarity of illustration. As shown FIGS. 45 and 46, the well cap has aplurality of small holes 55, 56, 57, 58, and 59. Inner tube 2 is shownextending through a hole cut to size for the outside diameter of theinner tube 2 extending from the well cap for connection to pipingassociated with mechanical heat transfer system. This design provides alow friction pressure drop through the cap structure. Alternatively, asingle medium size hole 60 can be formed, or drilled, in the cap forcommunication with the manifold structure, resulting in a little higherpressure drop due to frictional forces. When using the single mediumsized hole and a single pipe, threads can be used for establishing thepipe connection.

FIG. 47 shows weld joints 61 and 62 connecting a metal cap to a metalouter tube section 4 to hold the cap permanently in place.

FIG. 48 and 49 shows coaxial-flow heat exchanging structure containing ainner tube 2, fitted with compression ring 54 under a clamped well cap53. In this design, the cap structure 53 can employ an O-ring 54, orU-ring seal around the proximal end of the thermally-conductive outertube so as to prevent fluid leaks. The clamps 62 and 63 welded or boltedonto the outer surface of the thermally-conductive outer tube sectionare provided to prevent fluid pressure from forcing the well cap off thethermally-conductive outer tube section in cases of shallow helicaltubing depths or high fluid pressures. For permanent installations incement structures, the well cap structure can be fusion welded, as shownin FIG. 47 so as to reduce the risk of leaks.

FIG. 50 shows the coaxial-flow heat exchanging structure employing anexemplary manifold structure 64 comprising welded or threaded pipefittings connected to cap structure 53 and sealed by O-Ring 54.

FIG. 51 shows a pipe connection arrangement where the coaxial-flow heatexchanging structure uses tube fittings 66, 67, 68 and 69 welded to theside of the thermally-conductive outer tube section 4 for fluid inletthrough pipe 68 and 66, then through an internal reducing pipe elbow 70,and into the inner flow channel of inner tube 2. The heat transfer fluidis returned to the heat transfer fluid outlet 69 along the outer flowchannel between the inner tube 2 and the outer tube 4 through reducerfitting 67. This arrangement is suitable for use in foundationinstallations when the tube fittings are in a state of compression.Reference numeral 5 indicates an end cap welded on the distal end of theouter tube 4 to seal against leakage from or into the surroundingenvironment.

FIG. 52 shows the low pressure coaxial-flow heat exchanging structureusing a set of first tube fittings 75, 76 and 77 welded to the mediumsize hole in cap structure 53 for fluid injection into or withdrawal offluid from the outer flow channel, and a second set of tube fittings forfluid injection or withdrawal of fluid from the inner flow channel.

In FIG. 53, the coaxial-flow heat exchanging structure 78 is showninstalled in a deviated well bore to form a ground-loop system forexchanging heat energy with an aquifer below the Earth's surface. Toinstall this system, a well is drilled with a radius turn (approximately50 ft. radius) into the aquifer zone. Thereafter, the metalthermally-conductive outer tube 4 is cemented with sanded grout tosurface so as to prevent aquifer contamination and increase the heattransfer coefficient to the ground. After cementing operations, thethermally-conductive outer tube is cleaned with a mild acid solutionwith surfactant to remove mud, mill scale and grout tailings. Thehelical pitch and number of fins on the helically-finned tubingcomponent are selected to rotate the fluid at the desired circulationrate. Once these parameters have been determined, the helically-finned(insulated) inner tubing is inserted into the interior of the installedouter tube and run to the bottom of the outer tube shoe and sealed offat the thermally-conductive outer tube cap using fusion welding.

As shown in FIG. 53, the design goal for the ground/water source loop ofthe heat transfer system of the present invention 1 has been to provideenough heat-transfer surface area and ground/water volume to insure thecirculating fluid temperature of the ground/water source loop does notgo above/below the average ground temperature by 7° F. or 3° C., undercontinuous load during peak of the heating/cooling season. Bymaintaining a return fluid temperature within 7° F. or 3° C. of theground/water source temperature, the SEER rating of the heat pump systemwill be maximized for the whole heating/cooling season. A commercialobjective of the design has been to use a combination of metal andplastic tubing to increase heat transfer to/from the ground whilereducing the life-time cost of the ground loop which includes thecapital, maintenance and operational cost averaged over the life-time ofthe system.

If the time averaged heat and cooling loads are nearly equivalent overthe thermal seasons, then the core volume of the ground loop can bedesigned to store heat during the cooling season and, subsequently, theheat can be extracted from the core volume during the heating season. Ifthe time averaged thermal load is mostly heating or cooling, then groundloop is designed to transfer heat without significant storage in theground volume.

For small spikes over base load, larger well bore diameter or the ironmass in the foundation can be used for thermal storage to average outthe operational temperature of the fluid. It has been discovered thatwhen using a helical fin design and a slot (i.e. outer flow channel)aspect ratio (i.e. ratio of dimensions of the helically-extending outerflow channel) ranging from a 1 to 1 square to a 1 to 2.5 rectangle,tubing diameters can exceed 36 inches or 1 meter without significantlyreducing heat transfer coefficient to the ground/water source. For largespikes over base load, a larger tank volume can be added to the groundloop for additional thermal storage.

For an estimated yearly thermal load, a thermal simulator can be used todetermine the number wells used in the ground loop array, the amount ofthermal storage needed to average out the daily peak loads and theamount of core volume needed in the array to store heat from the coolingseason to use in the heating season. For large thermal projects, thesimulator can be used to optimize capital cost of drilling (horizontalwell bore length versus number of wells in array), material cost of thethermally-conductive outer tube (thermally-conductive outer tubediameter versus metal or plastic), the approach temperature of theground loop and the refrigerant used by the heat-pump system. However,the actual heat transfer rate and time coefficient of the ground-looparray of wells should be determined with a transient temperature test ofthe ground loop and the actual heat storage of the ground loop should bedetermined with a complete year of history of circulating fluidtemperature and load data.

The well design parameters such as grout thickness, thermally-conductiveouter tube material, helical pitch, number of helical fins, insulatedwall thickness of inner tube, and fluid composition can be optimizedusing analytical equations for steady state operation. Most of the wellarray design parameters such as well depth, well length, well spacingshould be optimized for the given aquifer properties with a thermalsimulator over a multi-year load to account for the thermal storage ofEarth and the seasonal transients. Most of thermal storage parametersfor the insulated volume of fluid in a tank or in the array of wellbores, or the insulated volume of concrete in the foundation, can beempirically fit with simple equations so that the peak loads can beaveraged over the daily operation of the heat pump. The design goal isto install a ground loop with thermal storage so that it can transferthe daily thermal load from the heat pump for the minimum capital costand operational cost.

As shown in FIGS. 67, 68 and 69, an array of similar wells can bedrilled and coaxial-flow heat transfer structures installed therein, andinterconnected to gathering lines for series or parallel operation as aheat exchanger coaxial-flow heat exchanging structures. Finally, theground loop is filled with an aqueous heat transfer fluid and the air isbled out of the high spots in the system to achieve optimum performance.Using the coaxial-flow heat exchanging structure of the presentinvention, the installation cost and material costs associated withconstructing deviated wells is substantially reduced.

FIG. 54 shows a natural gas dehydration system using mechanical heattransfer equipment 83 of the present invention, wherein a deviated well81 is drilled in an aquifer to create a ground loop employing thecoaxial-flow heat transfer system of the present invention.

FIG. 55 shows the coaxial-flow heat exchanging structure of the presentinvention 85 installed in a near horizontally bored well in the side ofa mountain, mesa, hill, or other man made earthen structure. In thisapplication, the well bore path is deviated to follow an aquifer zone ifavailable at the site. For buildings having a deep basement or built onthe side of a hill, the deviated well bores can be drilled in andthrough the wall of the basement. As shown the heat transfer fluidpiping is connected to mechanical heat transfer equipment 86.

FIG. 56 shows the coaxial-flow heat exchanging structure of the presentinvention installed within an earth, mud, aqueous solution or chemicalsolution. The coaxial-flow heat exchanging structure is capped below thesurface to prevent significant heat transfer to the ground/water surfaceor ambient atmosphere. For areas that have significant ice orfreeze/thaw movement, the distribution pipes 87 and 88 should beprotected against damage and, if possible, the structure should becapped below the frost line.

FIG. 57 and 58 shows the coaxial-flow heat exchanging structure of thepresent invention installed vertically, (although it can be horizontallyinstalled) in bridge piers and foundations, or bridge components andfoundations and piers of a building or other similar structure. The heatexchanger of the present invention can take advantage of the metal rebarused in the concrete to increase the effective surface area of the outertube and any thermal storage quality the concrete may have. Byinstalling the co-axial flow heat transfer structure in the ground orwater below the structure, the cement/concrete sheath can perform twofunctions: (1) structural support, and (2) heat transfer to the water orground. If the heating load is small enough and the temperaturedifference large enough, then the coaxial-flow heat exchanger can beused in the thermo-siphon mode using the density difference between coldand warm aqueous solution. Otherwise a coaxial-flow heat-pump can beused to increase the heat transfer rate, and as the piling spacing isvery close in building foundations, the whole volume of ground containedbetween the pilings can be converted to a thermal bank for peak loads oreven to store heat from the cooling season to be used in the heatingseason. Also, if the top of basement foundation is isolated withinsulation, then cement structure and some surrounding ground can beconverted into a thermal bank for peak load averaging during winterheating and summer cooling. The heat transfer fluid enters the co-axialheat transfer structure shown through pipe 87. The heat transfer fluidexits the output port of the co-axial heat transfer structure throughpipe 88.

FIGS. 59, 60 and 61 shows the coaxial-flow heat exchanging structure ofthe present invention suspended in an aqueous solution or mud, e.g. inboth horizontal and vertical orientations. In these applications, thethermally-conductive outer tube section has radially-extending metalfins arranged around its outer surface for the purpose of increasing theheat transfer area of the outer tube section 4, i.e. by making it behaveas an external thermo-siphon for aqueous solution circulation about suchmetallic fins. The width of such external metallic fins to its thicknessaspect ratio should be less than 10 to 1 so as to optimize the use ofmetal and heat transfer to the aqueous solution or mud. Forinstallations in bodies of water, se fins can be coated for anodeoperation to prevent bio-film growth and scaling, which reduces the heattransfer to the aqueous solution.

FIG. 59 shows a cross-section cut-line for a top view FIG. 60 and aco-axial heat transfer structure submersed horizontally in water, mud,or chemical. As shown, the heat transfer fluid enters through pipe 87and exits the structure through pipe 88. An external fin structure 91can be installed onto the exterior surface of the co-axial heat transferstructure 1.

FIG. 60 is a top cut-away view of FIG. 59 showing the externalradially-extending heat transfer fins 91 attached to the exteriorsurface of the co-axial heat transfer structure outer tube 4. The topview shows the a central tube 14 with standoffs 23, 24 and 25, as shownin FIG. 11 and 12, allowing a laminar fluid to flow through the centerinsulating central tube 14.

FIG. 61 shows the coaxial-flow heat exchanging structure of FIGS. 59 and60 installed in a bridge component or piling 92 and submersed below thewater line above the bridge component. As shown the external radial fins91 are arranged radially and laterally around the exterior of thecoaxial-flow heat exchanging structure outer tube. The heat transferfluid is circulated through the structure through pipes 87 and 88.

FIGS. 62 and 63 show small and large coaxial-flow heat exchangingstructures of the present invention installed in ground to prevent icingor snow accumulation on bridges, walkways (i.e. side walks, heavilytraveled intersections or steeply pitched roads and driveways). In suchapplications, the ground heat can keep the road surface from icing upand increase the evaporation rate of moisture on the road, providingnumerous safely benefits. During spring and summer operations, thesystem can thermally bank (i.e. store) heat for intermittent wintersurface de-icing. In order to reduce energy cost, the pump operation canbe remotely computer-controlled by the local authorities before the badweather conditions move in the area, causing the transfer of heat energyof and preventing the road conditions from becoming dangerous.

FIG. 62 shows a number of coaxial-flow heat transfer structures of thepresent invention, connected in series with pipe 93, installed withinand beneath a bridge component 90 for the purpose of circulating enoughheat transfer fluid, using pump 96, through a piped grid 94, sufficientenough to maintain the bridge floor 95 and walkway above freezingtemperatures.

FIG. 63 shows a number of coaxial-flow heat transfer structures of thepresent invention, connected in series with pipe 93, installed adjacenta bridge component 90 for the purpose of circulating enough heattransfer fluid, using pump 96, through a piped grid 94, sufficientenough to maintain the bridge floor 95 and walkway above freezingtemperatures.

FIGS. 64 and 65 show the application of a single coaxial-flow heattransfer structure 1 for a residential home. FIG. 64 shows a buildingwith a self-contained central air conditioning heat pump 97 equippedwith a water-cooled refrigeration condenser section therein. Throughpipes 98 and 99, pump 100 circulates a heat transfer fluid through thewater cooled refrigeration condenser and the coaxial-flow heat transferstructure 1 to either transfer heat into the earth or absorb heat fromthe earth for distribution within the interior spaces of the building.

FIG. 65 shows the application of a single coaxial-flow heat transferstructure 1 for a building. In this application, an optional thermalbank tank 103 is connected with pipes 102 and 103 provided for nighttime and mild climate cooling mode of operation during times whenelectrical energy expense is less for night time modes of operation, andcolder day time operation when solar panels can provide heat energy forhydronic heating modes of operation. The said modes of operation can becalled the economizer modes of operation. The solenoid valves are usedto valve the thermal bank tank either in series with the coaxial-flowheat transfer structure or parallel (shunted).

FIG. 66. shows the building of FIG. 64 but with a number of coaxial-flowheat transfer structures arranged in a parallel configuration withsupply pipes 98 and return pipes 99. This system configuration providesthree times as much thermal capacity as shown in the system of FIG. 64.

For cooling applications, the addition of soluble gases to theaqueous-based fluid improves the heat transfer to the ground/watersource. As the pressure increases with depth of fluid column, thesoluble gases are adsorbed by the aqueous fluid; the gases release theirstored heat to the fluid, and in turn raise the temperature of the fluidwhich in turn increases the temperature differential between the fluidand the ground/water source. Carbon dioxide (CO2) and ammonia (NH3)gases foamed with surfactants create stable aqueous-based fluids used inthis absorption process. The fluid return line requires insulation toprevent the heat absorption of heat as the gases come out of solutionwhen the fluid returns to the surface. The adsorption and de-sorptionprocess acts like a low differential temperature refrigerant cycle, butit can be quite effective in increasing the heat transfer in theground/water source loop.

For heating applications, the addition of solid particles to the heatexchanging flow can increase the heat capacity of the aqueous-basedfluid. Micron sized heavy metal or metal oxide particles can be mixedwith the aqueous based fluid and suspended with a shear thinning polymersuch as xanthan gum or borate cross-linked polymer. The fluid must bekept in motion or the particles will eventually settle out and plug thebottom of the co-axial flow heat transfer structure. Micron-sized glassspheres containing a low melting point salt can also be used to increasethe heat capacity of the fluid while maintaining a particle specificgravity close to 1. Particle specific gravities near to 1 will preventsettling of the particles in the aqueous fluid, thus allowing a groundloop section to be shut down with out the danger of plugging the heatexchanger with settled particles. Field experience has shown that thecomposition of the aqueous-based fluid should remain simple to reducecapital cost and that increasing fluid flow rate is a better solution toincrease heat capacity of the system, except where very high heattransfer rates are required.

FIGS. 67 and 68 show an application of array pad-drilling nine deviatedwells, to minimize the ground surface impact while maximizing the volumeof ground contacted by the well bore. FIG. 68 is a front view of thevertical coaxial-flow heat transfer structures shown in FIG. 67connected in series where one is a vertical well bore and the other is adeviated well bore. Long term operation allows the coaxial-flow heattransfer structure to thermally bank (i.e. store) heat during thecooling season for use during the winter season. For cooling loads only,a shallow horizontal coaxial-flow heat transfer structure can be addedto the coaxial-flow heat transfer array shown in FIG. 67 for thepurposes of removing heat from the thermal bank during the winterseason. The pad drilling process indicated in FIG. 67 also has theadvantage of reduced heat loss from horizontal gathering of piping andreduced risk of accidental damage from contractor digging operations.

FIG. 69 shows a system of eleven deviated wells according to the presentinvention, connected together in a two series array configuration. Pipe98A and 99A supply and return heat transfer fluid to the center array,while pipes 98B and 99B supply and returns heat transfer fluid to theouter array. Each well contains a coaxial-flow heat transfer structureof the present invention. As shown, the coaxial-flow heat transferstructure of the present invention can be combined in various ways torealize improved heat transfer systems and networks capable of handlingdiverse thermal loads.

FIGS. 70 and 71 show, respectively, applications using seawater orballast water in a condensing system and heat sink for gas dehydration,and oil de-waxing used on a drilling platform 107. In such applications,the coaxial-flow heat exchanging structures 1 of the present inventioncan be used on off-shore drilling facilities floating or supported onpier 108 to extract heat from the gas to cause the temperature of thegas to drop which then condenses water vapor and/or light hydrocarbonvapors into disposable liquids. The coaxial-flow heat exchangingstructure can also be used to extract heat from oil with a coldstructure to cause the wax to build up on the cold finger structureinstead of on the pipeline wall transporting the oil to shore 110. Areversible refrigeration condensing system 109 (i.e. heat pump)connected to the coaxial-flow heat exchanging structure can be used toheat the oil to prevent or clean the wax buildup on the pipeline wall.The coaxial-flow heat transfer structure can be submerged in the openseawater, as shown in FIG. 70, or submerged in the ballast water in thestructure as shown in FIG. 71. For open sea water, as shown in FIG. 70,the exterior of the coaxial-flow heat exchanger is coated for anodeoperation to prevent bio-film growth on the outer tube surface thereof.Using a closed-loop coaxial-flow heat exchanging structure submerged inseawater in locations teaming with sea life, greatly reduces themaintenance cost of other types of heat exchangers especially, the typeof heat exchangers used in power plants.

FIG. 72 illustrateas how multiple coaxial-flow heat exchangingstructures 1 can be installed below the ocean floor or plowed into a mudlike along shore to prevent conditions such as over heating or excessivecooling of the surrounding sea water which can compromise biologicallife forms residing therein. Coaxial-flow heat exchanging structuresused on or in connection with oil and gas production systems shown inFIGS. 70, 71 and 72 can be as shown or combinations of floating,hanging, buried and other field constructed applications of the presentinvention.

FIG. 73 shows the application of the coaxial-flow heat exchangingstructure of the present invention 1 in a ground-loop heat exchangingsystem used on-shore for pipeline quality gas dehydration. As shown,natural gas produced from a remote off-shore platform 107 is pumped toan on shore plant through pipe 110 to dehydration processing equipment111 and delivery to process and distribution facilities through pipe112.

FIG. 74 shows a platform, or shore based, liquid natural gas (LNG)receiving port, gasification and storage facility 113 supported on piers114. The Special Provision for Monitoring (SPM) 115, normally, is in thesame location or near to the point where liquid natural gas tanker shipsoff-load the liquid natural gas for gasification of storage. The naturalgas can be stored in a salt cavern 124 through pipe 122, located in asalt cavern storage area encompassing one or more salt caverns, or thenatural gas can be fed directly into the gasification process equipmentlocated in the facility. The liquid natural gas is fed through pipe 116to the gasification equipment, such as gas turbine engines, pumps andgenerators, as the natural gas changes in state from a liquid to a gas(evaporates) inside the heat exchanger 117 it requires a large amount ofheat to cause the change in state. Generally, sea water is taken intothe heat exchanger where the heat contained in the water is transferredinto the gas. The sea water is then returned back to the sea locallywhich can have negative environmental consequences, damaging the localaquatic life forms and having a biological impact thereof. To preventthis problem, a heat transfer fluid is circulated through the heatexchanger 117 via pipe 121 from a subsurface grid (array) of a number ofdeviated coaxial-flow heat transfer structures 81 of the presentinvention. As shown, these structures 81 are connected together inparallel, with manifold 119, and a secondary array of a number ofsuspended coaxial-flow heat transfer structures 1, shown connected inparallel with manifold 120. In this arrangement, the heat transfer fluidtravels through pipe 118 back to the heat exchanger 117 for heatdissipation and recirculation through the coaxial-flow heat transferstructures shown. If the gasified natural gas is not to be stored butpiped to a processing and distribution center, it is normally pumpedinto on shore or undersea pipeline 125 to a facility on shore. Using agrid of co-axial flow heat transfer structures, installed in deviatedwells, beneath the mud line of the ocean floor, prevents damage to theaquatic environment and provide a source of heat rather than burning aportion of the product (natural gas) during the gasification process.The coaxial-flow heat transfer structure shown in FIGS. 83 and 84 can beused to replace conventional heat exchangers currently in use.

FIG. 75 shows a pair of coaxial-flow heat exchanging structures 130 and138 of the present invention connected to a skid-mounted gas dehydrationand condensate separation system 127 (e.g. in an application having asingle well or gathering system). The gas enters the system from a well126 and delivered to process and distribution facilities through pipe144. In this system, natural gas and other liquids are produced from thewell 126 that is completed in the gas zone. The natural gas movesthrough the separator 128, typically a tube 120 and shell type assembly,where brackish water and hydrocarbon liquids are separated from thenatural gas. A heat transfer fluid cooled to a temperature substantiallyless than the gas temperature by the coaxial-flow heat transferstructure 130 is circulated to the tubes 129 inside the separator shell,via pipe 132 and returned to the coaxial-flow heat transfer structure130 through pipe 131, causing brackish water and hydrocarbon liquids tocondense from the gas for collection for disposal. The natural gas thenmoves through pipe 134 into the evaporator section 135 of therefrigerated dehydrator 136 where the temperature of the gas is reducedfurther to condense the water vapor and heavier hydrocarbon vapors fromthe gas. As shown, heat transferred into a heat transfer fluid from thecondenser section 137 travels through pipe 139 to coaxial-flow heattransfer structure 138, where the heat is dissipated into the Earth, andthe cooled heat transfer fluid returns back to the condenser sectionthrough pipe 140. Finally, the partially dehydrated natural gas passesthrough pipe 142 and is then polished by a small glycol unit 143 toremove the last traces of water vapor for shipment via natural gasproduction supply lines.

Notably, in the natural gas dehydration system shown in FIG. 75, thedeviated well provides fluid, heated to ground temperature, for thepurpose of dehydrating natural gas in a natural gas productionenvironment. However, for other oil field heating and coolingapplications, additional large surface holes can be drilled and thecoaxial-flow heat transfer structure of the present invention installedand thermally cemented therein.

FIG. 76 shows a submarine with a seawater intake 146 taking in seawaterand delivering it to seawater heat exchangers 1 of the present inventioninstalled in a seawater heat exchanging system 147 aboard a submarinefor centralized and zoned air conditioning and equipment coolingnormally utilizing heating and cooling heat exchangers 149, (also shownin FIGS. 78 through 82). The conditioned air is then distributed tospecific locations aboard the submarine by air distribution ducting 151.In addition to increased heat transfer efficiency, the coaxial-flow heatexchanger helps to reduce noise generation and increase the safety incase of a hull breach. After use, the seawater is then returned to thesea through outlet 148.

FIG. 77 shows a submarine with a seawater intake 152 taking in seawaterand delivering it to seawater heat exchangers 1 of the presentinvention. As shown, these exchangers are installed in a seawater heatexchanging system 153 aboard a submarine for centralized and zoned airconditioning and equipment cooling normally utilizing heating andcooling heat exchangers 155 and 156, (also shown in FIGS. 78 through82). In addition to increased heat transfer efficiency, the coaxial-flowheat exchanger helps to reduce noise generation and increase the safetyin case of a hull breach. After use, the seawater is then returned tothe sea through outlet 154. It is suggested that a mixed oxidant isinjected into the seawater or a saltwater chlorinator so as to treat theseawater and prevent bio-film buildup on the fins. The heated seawatercan be pre-diluted with fresh seawater to prevent production of athermal plume around the submarine.

FIG. 78 is an elevated cross-sectional side view a coaxial-flow heattransfer structure of the present invention. As shown the structure 1Ais a component of a heat exchanger assembly shown in FIGS. 80 through 87showing the heat transfer fluid (i.e. liquid refrigerant from arefrigeration condenser) (i) entering through tube 159, having aturbulent flow profile as shown in FIGS. 38 and 41, (ii) passing throughthe outer flow channel along the outer tube 4 inside surface, and (iii)returning through the helically-finned center tube 2, having a laminarflow profile (as shown in FIGS. 1 and 1A) to the heat transfer fluidsource (i.e. refrigeration compressor) through pipe 158.

FIG. 79 is an elevated cross-section, side view a coaxial-flow heattransfer structure of the present invention. As shown the structure 1Ais a component of a heat exchanger assembly shown in FIGS. 80 through 87showing the heat transfer fluid (i.e. liquid refrigerant from arefrigeration condenser) (i) entering through tube 162, having a laminarflow profile as shown in FIGS. 1 and 1A, (ii) passing through thehelically-finned center tube 2, and (iii) returning through the outerflow channel along the outer tube 4 inside surface, having a turbulentflow profile (as shown in FIGS. 38 and 41) to the heat transfer fluidsource (i.e. refrigeration compressor) through pipe 161.

FIG. 80 is a front and cross-sectional view of an array of coaxial-flowheat transfer structures 1A of the present invention, arranged in whatis traditionally called a horizontal or block style heating or coolingcoil. These coaxial-flow heat transfer structures are securely held inplace by compression fitted or welded openings in end plates 163 and164. The inner tube section of each coaxial-flow heat transfer structure158 is connected to a manifold tube 165 to provide heat transfer fluidflow through each coaxial-flow heat transfer structure. Preferably, theheat transfer fluid flow is evenly distributed through each coaxial-flowheat transfer structure in the assembly into manifold tube 165. Also,the outer flow channel of each coaxial-flow heat transfer structure isconnected by a tube 159 to a manifold tube 167 having an inlet 168 toprovide heat transfer fluid flow through each coaxial-flow heat transferstructure. Preferably the heat transfer fluid is evenly distributedthrough each coaxial-flow heat transfer structure. While travelingthrough each outer flow channel, as described in FIGS. 38 and 41, theheat transfer fluid is guided by helical fins 3 and transfers heatenergy into air, fluid or gases passing over fins 157 attached to theexterior surface of outer tube 4 of the coaxial-flow heat transferstructures 1A mounted in the assembly. The horizontal coaxial-flowcooling and heating coil of the present invention can be used totransfer heat into or out of air, fluid or gas passing over its externalsurfaces. The horizontal cooling and heating coil can also be used totransfer heat into or out of air, fluid or gas passing over it bycirculating a or metered refrigerant into tube 168 provided therefrigerant can evaporate while passing through the coaxial-flow heattransfer structures 1A mounted in the assembly. The horizontal heatingor cooling coil of the present invention can be constructed of a varietyof materials consisting of metallic and plastic components, consideringcompatibility of materials and heat transfer fluids and refrigerants.This embodiment of coaxial-flow heat transfer structure can also be usedas a radiator to cool a combustion engine.

FIG. 81 is an end view of the horizontal heating or cooling coil of thepresent invention shown in FIG. 80. The end plate 164 is shown holdingfour coaxial-flow heat transfer structures 1A in their respectivepositions in the assembly. FIG. 81 shows the tube 166 of manifold tube165 extended at an angle from the manifold tube 165 and the alignment ofmanifold tube 165 with each coaxial-flow heat transfer structure tube158. FIG. 81 also shows the tube 168 of manifold tube 167 extended at anangle from the manifold tube 167 and the alignment of manifold 167 witheach coaxial-flow heat transfer structure tube 159.

FIG. 82 shows the location of holes 169, 170, 171 and 172 punched in theend plate 163 so as to hold the coaxial-flow heat transfer structures inplace.

As shown in FIG. 83, a plurality of coaxial-flow heat exchangingstructures 1A are contained in a pressure vessel 173 which is used as anaqueous-based fluid-to-fluid, fluid to air, and refrigeration evaporator(chiller) or condensing heat exchanger (tube and shell heat exchanger)having a heat transfer fluid (i.e. refrigerant) inlet tube 168 and aheat transfer fluid (i.e. refrigerant) outlet tube 166.

As shown in FIG. 84, process fluid enters through inlet tube 176 to beheated or cooled as it passes by the fins of the coaxial-flow heattransfer structures 1A. The entering process fluid side of the pressurevessel is separated by the outlet side by separator plate 175. Afterpassing over the fins of the coaxial-flow heat transfer structures theconditioned process fluid exits the assembly through tube 177. End plate164 is welded to the pressure vessel along weld bead 174 to preventleakage of the process fluid.

In FIG. 85, two coaxial-flow heat transfer structures (functioning ashorizontal heating and cooling coils) are connected together at an anglewith brackets 185 and 187 which are secured to end plates 164 withscrews (i.e. rivets or spot welding) 186 and 188. In this application,the heat exchanger (heating and cooling coil) is configured in an ‘A’frame style. The two coaxial-flow heat transfer structure (i.e.horizontal heating or cooling coils) are connected/plumbed in a parallelconfiguration having both manifold tubes 165 and 179 connected togetherby tube 180 forming a common outlet connection providing a combinedfluid flow through tube 178. Manifold tubes 167 and 181 are connectedtogether with tube 182 at wye connector 183 providing combined flow ofheat transfer fluid into tubes 167 and 181 from tube 184.

As shown in FIG. 86, an array of coaxial-flow heat transfer structures1A of the present invention are assembled as components in the “A” styleheating and cooling coil shown in FIG. 85. The coaxial-flow heattransfer structures are securely held in place by compression fitted orwelded openings in end plates 163 and 164. The inner tube of eachcoaxial-flow heat transfer structure is connected to a manifold tube 179to provide a heat transfer fluid flow through each coaxial-flow heattransfer structure 1A. Preferably, the heat transfer fluid flow isevenly distributed through each coaxial-flow heat transfer structure inthe assembly. As shown, each coaxial-flow heat transfer structure flowchannel is connected by an inlet manifold tube 181 having an inlet 184to provide heat transfer fluid flow through each coaxial-flow heattransfer structure. Preferably the heat transfer fluid is evenlydistributed through each coaxial-flow heat transfer structure in theassembly. While traveling through each flow channel, the heat transferfluid can transfer heat into air, fluid or gases passing over finsattached to the outer tubes of the coaxial-flow heat transfer structuresmounted in the assembly. The horizontal coaxial-flow cooling and heatingcoil of the present invention can be used to transfer heat into or outof air, fluid or gas passing over its external surfaces. The horizontalcoaxial-flow cooling and heating coil of the present invention can alsobe used to transfer heat into or out of air, fluid or gas passing overit by circulating a or metered refrigerant into tube 184 provided therefrigerant can evaporate while passing through the coaxial-flow heattransfer structures 1A mounted in the assembly. The coaxial-flow heatingor cooling coil of the present invention can be constructed of a varietyof materials consisting of metallic and plastic components, consideringcompatibility of materials and heat transfer fluids.

As shown in FIG. 87, the two horizontal cooling coils 199 are connectedat an angle with brackets 189 and 191 which are secured to end plates163 with screws (i.e. rivets or spot welding) 190 and 192.

In FIG. 88, a building 193 is shown with a central air conditioningsystem comprising an electric or gas furnace with an ‘A’ style heatingand cooling coil 199 (as shown in FIG. 86 and 87) arranged in the airflow provided by blower 198. The air passing through the heating andcooling coil 199 is evenly distributed through air ducts 200 and 201.The outdoor aid condensing unit, (i.e. heat pump) is connected to theheating and cooling coil with a liquid refrigerant tube (high side line)196 and a return tube (suction line) 197.

As taught in the above illustrative embodiments, the coaxial-flow heatexchanging structures of the present invention can be manufactured invarious lengths, for example, in ten, twenty or thirty foot lengths,using plastic extrusion techniques, which are then joined and fusedusing various possible techniques (e.g. PVC cement, ultra-sonic welding,adhesive bonding using glue, etc.). However, in alternative embodimentsof the present invention, the coaxial-flow heat exchanging structure ofthe present invention.

For example, as will be described in greater detail below, the helicallyfinned inner tubing component, installed within the outer tube sectionof the coaxial-flow heat exchanging structure, can be manufactured asrelatively short (single or multiple) fin segments that are then appliedto the outer surface of flexible inner tubing, as shown in FIG. 89.Thereafter, the flexible tubing, with the applied helical fin segments,can be wound up on a storage spool, and subsequently removed andinstalled within the outer casing of the coaxial-flow heat transferringstructure that has been installed within a bed of thermally conductivecement pumped into well bore at an installation site. Technical detailsof this embodiment of the present invention will be describedhereinafter.

FIG. 89 shows a segmented helically-finned flexible inner tube section206 employed in the outer tube section of the coaxial-flow heatexchanging structure of FIG. 90. Reference numeral 202 indicates therepeated segments of a single helically-extending fin structure, 203 and204. Reference numeral 205 indicates the smooth section in the outerflow channel where the wakes of fluid flow, from each fin, mix beforebeing cut once again by the next set of fins. The segmented helical finsallow the fluid flow to transition from laminar to turbulent-like flowat lower Reynolds numbers, while moderately increasing heat transfer andfriction pressure drop. Preferably, the dimensionless twist ratio, y, ofthe fins should range from about 2 to 8, while the dimensionless spacingratio, z, of the fins should range from about 2 to 10. In theillustrative embodiments, calculations indicate that the segmented finsshould enhance heat transfer by a factor of about 1.1 to 1.5, whileincreasing the friction pressure drop by a factor of about 1.2 to 1.9when compared to a continuous helical fin type center tube.

To create a stabilized helical flow within a coaxially-extending outerflow channel, the fluid should preferably travel at least ½ rotation or180 degrees per linear foot of fluid travel. For a large diameter outertube section, the number of fins used in the outer flow channel isselected so the slot width to depth ratio ranges from about 1.0 to 3,while the slot length to depth ratio ranges from about 1.5 to 6.Otherwise, too few fins or too many fins create laminar slot flow havingminimal or no rotational component, providing additional frictionpressure drop, and offering minimal heat transfer enhancement.

FIG. 90 shows the segmented helically-finned inner tubing section 2installed in outer tube section (i.e. casing) 4 of the coaxial-flow heatexchanging structure of FIG. 1. Reference numerals 203 and 204 indicatethe enhanced heat transfer zones of the outer tube 4, while referencenumeral 205 indicates the remixing zone provided within the heattransfer structure of the present invention. The mixing zone allows thecore fluid in the slot between the helical fins 3 to mix with the fluidthat contacts the wall of the outer tube section 4, thus increasing heattransfer. Reference numeral 206 indicates the fluid entering theinsulated inner tubing section 2, whereas reference numeral 207indicates the fluid exiting the helically-extending outer flow channel.

FIGS. 91 and 92 shows an example of segmented helically-finned innertubing where the segments 203 and 204 are made from extruded pieces ofplastic material. This construction method is suited for large diameterthermal storage well bores where the tubing or hose cannot be rolledonto a spool. FIG. 91 shows separate extrusions for the finned 203 and204 and smooth inner tube sections 2, while FIG. 92 shows an integralsmooth 205 and finned section 204. Reference numerals 203 and 204indicate the single helically-finned inner tube section, while referencenumerals 2 and 205 indicate the smooth section thereof. Referencenumeral 208 indicates the threaded or slip couplings used to join theinsulated inner tube sections 203, 2 and 204 together. The couplings canbe glued or plastic welded together. Segments shown in FIG. 91 and 92can be made of a metallic material and welded or threaded together tolength.

FIG. 93 shows that the single wrap-around single fin 211 and itsintegrated base layer 210 can be extruded flat and parallel while heatedto its plastic point, and then wrapped around a mandrel so as to givethe fin a helical pitch to match the tubing or hose size to be employedwithin a coaxial-flow heat exchanging structure as shown in FIG. 96.Reference numeral 209 represents the cut length of the segment to beshaped. Preferably, the diameter of the plastic fin shaping mandrelshould be about 5-10% smaller than the smallest installed inner tubingor hose in the field because air gaps prevent good glue adhesion. If thefin is made of metal, then the mandrel should be about 5% larger thaninsulated tubing and it should be tack welded to the tubing wall.

FIG. 94 show a wrap-around single fin segment for application about asection of flexible tubing or hose to be used to realize the insulatedhelically-finned inner tubing component employed in the coaxial-flowheat exchanging structure of FIG. 89. The single fin 211 and base 210are adapted for flexing due to the gap indicated by reference numeral212. The fin can be glued or plastic welded to a hose to preventmovement during installation and use. With this design, the flexiblehose with fins can be spooled for shipment to the installation site andunspoiled without damage to the fin shape during installation.

FIG. 95 is a wrap-around segment shown in FIG. 93 and 94 but withwrapped twist in the opposite direction around the tubing or hose.

FIG. 96 shows a length 213 of segmented coaxial-flow heat transfercenter tube and helically extended finned 211, single wrap-around finsegments 210 creating a mixing zone 205 between turbulent zones 203 and204 applied on a section of inner tubing or flexible hose 2 installed ina section of outer tube (i.e. casing). The fin segment 210 can be gluedor plastic welded to the flexible hose and rolled on a spool forinstallation in the field.

FIG. 97 shows a wrap-around single fin segment 210 having a left handtwist, in comparison with a right hand twist, provided to thewrap-around fin segment shown in FIG. 96. The alternating left and righthand twist combination shown in FIG. 97 is used for large thermal wellbores, or where the fluid has a high viscosity or where a laminar flowregime exists in the outer flow channel and should be turbulentlydisrupted.

FIG. 98 shows an elevated side view of a multiple-finned segment appliedabout a section of inner tubing or hosing to be used to realize thethermally-insulated helically-finned inner tubing component employed inthe coaxial-flow heat exchanging structure of FIG. 96. As shown, theglued-on segment is used for small annular widths where the single finsegment could not create helical flow for enhanced heat transfer. Thesmall annular widths are required for minimum flow velocity when lowflow rates are used in large diameter thermal storage wells or whenfluids have high viscosity. As shown, reference numeral 216 shows theflexible base, while reference 217 points to the glue seam. Referencenumeral 218 points to the tab and slot used to snap together the segmenton the inner tube or hosing section during the gluing or weldingprocedure.

FIG. 99 shows a segment 219 like the one shown in FIG. 98 except segment219 has no tab and slot shown in FIG. 98. The removal of the tab andslot can facilitate the high speed welding of numerous segments onto thesurface of rolled tubing by an automatic welding machine shown in FIG.104.

FIG. 100 shows a multiple-finned segment applied about a section ofinner tubing or hosing 2 to be used to realize the thermally-insulatedhelically-finned tubing component employed in the coaxial-flow heatexchanging structure of FIG. 96. Reference numeral 220 indicates theflexible plastic base while 3 indicates the smooth fin wall. If tallfins are used, then there can be some buckling of the fin wall when thesegment is wrapped around the inner tube or hose section if the storagespool is too small in diameter. Reference numeral 221 indicates the taband slot used to snap together the opposing ends of the multi-finnedsegment.

FIG. 101 shows a molded or extruded multiple-finned segment employedwithin a coaxial-flow heat exchanging structure as shown in FIG. 96. Asillustrated, this segment is provided with a number of fins after it hasbeen molded or cut from a continuous sheet. Reference numeral 222indicates the flexible base, whereas reference numeral 223 indicates oneof the fins. Reference numerals 224 and 225 point to the tab and slotused to join together the edges while the segment is glued to the outersurface of the inner tube section. Unlike the single fin segment asshown in FIG. 93, the multiple-finned segment length 226 is plus orminus 2 percent for the outside diameter of the inner tubing sectionthat it will be glued to in the field or mechanically as shown in FIG.104. For factory created multiple-finned segmented inner tube sections,the base of each segment can be straight cut without gluing tabs, asshown in FIG. 99, to length from a roll of molded material and plasticwelded to the flexible inner tubing.

FIG. 102 shows a cross-sectional view of the coaxial-flow heatexchanging structure of the present invention employing segmented-typesingle helically-extending fin segments, as shown in FIG. 98, installedon the surface of an inner tube section 2. As shown, the finned innertube section is installed within a thermally-conductive outer tubesection (i.e. casing) 4, that has been cemented within a well bore, anda re-mixing zone 230 being provided between its helically-extendingouter flow channel. Reference numerals 228 and 229 indicate the segmentlengths, while reference numeral 230 indicates the spacing length of thefluid re-mixing zone. As shown, the base 222 from which fin 213 extendsis glued to the outer surface of inner tube section 227. For similar finpitch and number, the extruded segmented fins in FIG. 98 and flexiblesegmented fins in FIG. 102 should demonstrate substantially the samefluid heat transfer performance through the outer wall of the outer tubesection.

FIG. 103 shows the coaxial-flow heat exchanging structure of the presentinvention employing segmented single fin segments having alternatingleft and righted handed twists. As shown, the helically-finned innertube section 231 is installed within the outer tube section 4, and are-mixing zone 234 provided along the helically-extending outer flowchannel. The spacing length of the remixing zone is indicated byreference numeral 234. As shown, reference numerals 232 and 233 indicatethe right and left handed twist fins. This arrangement is used forenhancing heat transfer in large-diameter outer tubes, with low-velocitylaminar flow or highly viscous flow characteristics in thehelically-extending outer flow channel. This arrangement can be alsoused to enhance heat transfer in short metal pipe runs along beaches,river banks and shores where there is natural water movement in the soilto remove the heat from the near well bore area.

FIG. 104 shows a machine 235 designed to automatically attach single ormulti-finned segments 239, fed into machine 235 through bin 240 onto theouter surface of flexible inner tubing 236 as the inner tubing is beingrolled off a spool 237 supported on a stand 238. As shown, the assembledsegmented finned tubing structure 241 is then rolled up onto a storagespool 242 supported by stand 243, for subsequent transport or shipmentto a well site.

FIG. 105 shows a ground-supported spool of coaxial-flow heat exchangingmulti-finned segments of the present invention, being loaded into acasing that has been installed within a well bore filled withthermally-conductive cement. Reference numeral 244 indicates a sectionof tubing (i.e. hose) with the segmented fins attached thereto.Reference numeral 245 indicates the manual or power spool used to lowerand raise the segmented fin tubing into the outer casing 248. In theillustrative embodiment, a pulley or wheel 247 is used to preventpinching the segmented finned inner tubing as it is lower into the outertube section (i.e. casing). The base 246 of the manual or power spoolshould be massive enough or anchored to the ground so as to preventsliding as the segmented finned tubing is lowered into outer tubesection 248 cemented into the ground, during construction of thecoaxial-flow heat transfer structure of the present invention.

FIG. 106 illustrates how fluid inlet and outlet ports (i.e. well head)associated with the coaxial-flow heat transfer structure of the presentinvention can be constructed from conventional metallic or plasticfittings. Specifically, as shown, a tee 250 is threaded, welded, orglued to the proximal end of the outer tube section 4. Multi-finnedinner tubing section 2 passes through a reducer fitting 249 extendingbeyond the top run of the tee a short distance 2 for connection to theheat transfer fluid supply piping. Other pipe fittings, not shown, suchas reducers, bell pipe fittings and nipples can be connected to thebranch of the tee returning the heat transfer fluid back to heating,cooling or other heat transfer devices and equipment. The well head canbe installed subsurface to prevent damage thereto due to freezing orvehicular traffic. The direction of heat transfer fluid flow shown inFIG. 106 can be reversed resulting in the same heat transfercharacteristics.

FIG. 107 shows a coaxial-flow heat transfer structure employing a numberof non-helical turbulence generators 252 arranged on the outer surfaceof the inner tube section. As shown, multiple discrete turbulencegenerators 252 of identical or different lengths can be strategicallyplaced on the exterior surface 251 of the inner tube 2 so as to create asignificant amount of turbulence along the outer flow channel, betweenthe inner tube and the outer tube 4. The turbulent flow structure showncan be installed inside the entire length of the outer tube section 4 orconnected in combination with other said segments along the length aspart of the coaxial-flow heat transfer structure.

FIG. 108 shows the coaxial-flow heat transfer structure of the presentinvention shown in FIG. 107.

FIG. 109 shows the outer tube 4 and the turbulent flow generators 252.

FIG. 110 shows a large diameter coaxial-flow heat transfer structurecomprised of a number of helically extended fins 3, between the centertube surface 2 and the outer tube 4 inner surface.

In FIG. 111, a coaxial-flow heat exchanging structure of the presentinvention is shown, wherein the outer tube section 4, inner tube section2 and helically-extending fins 3 are formed as a unitary product using aplastic extrusion process. Notably, a rotatable die structure will beused to manufacture this product.

FIG. 112 is a cross-sectional side view of the coaxial-flow heattransfer structure of the present invention shown in FIG. 111.

FIG. 113 is a cut-away view, section B-B, of the coaxial-flow heattransfer structure of the present invention shown in FIG. 111 havinginternally extruded flow guide fins 3 between the inner flow channeltube 2 and outer tube 4 and showing the center tube openingtherethrough.

In FIG. 114 is a perspective, partially transparent, view of acoaxial-flow heat transfer structure showing the outer tube 4 and acoaxial-flow heat transfer structure wherein the inner tube section 2has multiple rows of fin segments 254 helically extending along theouter FIGS. 115 shows a coaxial-flow heat transfer structure employing ahelical turbulence generator structure 255 that is constructed from asolid, hollow-flat, or tubular metallic, plastic or fiberglass materialand installed between the inner tube section 2 and outer tube section 4.As in the other illustrative embodiments described above, the helicalstructure 255 creates helically-extending outer flow channel(s) alongwhich turbulence fluid flows are generated.

FIG. 116 shows a coaxial turbulent flow generator having a number ofhelically-extending (flow guide) fins 257 and 258 extending from a solid(or hollow) center core shaft 256. The turbulent flow generator isdesigned for insertion along the central axis of tubular heat exchangers(e.g. tubes or pipes) which require repair or otherwise require anincrease its efficiency through the generation of an optimum turbulencein the fluid flowing therethrough. Installation environments include,for example: “U” tube type ground source loops as shown in FIG. 117;tube and shell heat exchangers found in heating, cooling andrefrigeration systems; combustion engine radiators; and a variety ofother tubular heat transfer systems and components. It could be lessexpensive to add to or modify heat exchangers of these types using thisturbulence flow generator of the present invention rather than replacingthe heat exchanger or radiator which can be more costly. The number offlow guide fins, helically-arranged along the length of the center coreshaft, can be increased or decreased to produce the desired heattransfer rate and heat transfer fluid flow rate. The coaxial turbulentflow generator shown can be constructed of a plastic or metallicmaterials depending on fluid and other material compatibilities.

In FIG. 117, there is shown a conventional heat pump ground source loopnormally fabricated in the field using commonly available tubing andfittings such as PVC, polypropylene, polyethylene, copper, aluminum, andsteel pipe and fittings. A heat transfer fluid is pumped into and out oreither of tubes 260 and 261. The “U” bend fitting shown as 262 can bemade from a converted plumbing fitting called a “P” trap, but is usuallyfabricated using two 90 degree (quarter bend) ells glued or welded inplace to form a “U” bend as shown. By installing the coaxial turbulentflow generators 259 of the present invention along the linear lengths ofthe ground loop, the laminar flow profile along the “U” tubes willtransition into turbulent flowing profiles shown in FIGS. 38 and 41,thereby increasing the heat transfer efficiency of the tube. The numberand thickness of the flow guide fins and the helical linear pitch of theflow guide fins 157 and 158 can be adjusted during manufacturing toarrive at a desired turbulent flow profile inside flow channels existingbetween the flow guide fins and the inside diameter of the tube or pipeinto which the coaxial turbulent generator is to be inserted. Thecoaxial turbulent generator can be made from plastic, metal or othermaterials, and can be made flexible so that it can be rolled up intospools for storage and delivery to site locations where it is to bedeployed.

FIG. 118 shows an air conditioning system employing a system ofcoaxial-flow heat transfer structures of the present invention. Thecoaxial-flow heat transfer structures 308, 309 and 310 function as aheat transfer sub-system connected to a water-cooled ground sourcecondensing unit 283 found on a typical direct expansion air conditioningsystem where an electric or gas fired furnace is used during the heatingmode of operation. The heat transfer fluid being pumped by pump 269through the ground loop coaxial-flow heat transfer structures firstpasses through pipe 270 and a hydronic air vent 271 to remove air thatmight be in the fluid piping system.

In the cooling mode, during times when the outdoor air temperature ishigher than the heat transfer fluid entering the coaxial-flow heattransfer structures, through pipe 272, valve 268 is open and valve 267is closed. When the outdoor air temperature is below the temperature ofthe heat transfer fluid valve 268 is closed and valve 267 is openallowing the heat transfer fluid to flow through outdoor air heatexchanger 266 allowing heat to be extracted from the heat transfer fluidbefore it enters the coaxial-flow heat transfer structures through pipe272. This function increases the heat transfer efficiency of the entiresystem and promotes heat recovery time of the ground loop and extendingthe overall life of the coaxial-flow heat transfer structuresconductivity. The outdoor air heat exchanger 266 can be constructedwithout a fan (i.e. natural draft) or with a fan (i.e. forced draft).

In the cooling mode, heat is extracted from the heat transfer fluid asit passes through coaxial-flow heat transfer structures. The heattransfer fluid leaving the coaxial-flow heat transfer structure 308 istransferred to the coaxial-flow heat transfer structure 309 by pipe 173where more heat is extracted from the heat transfer fluid. The heattransfer fluid leaving coaxial-flow heat transfer structure 309 istransferred to coaxial-flow heat transfer structure 310 by pipe 274where more heat is extracted from the heat transfer fluid into theEarth. The heat transfer fluid is returned to the water cooled condenserof the air conditioning condensing unit 283 through pipe 275. The heattransfer fluid direction of flow can be reversed entering the groundsource wells through pipe 275 and exiting the wells through pipe 272.

As shown in FIG. 118 high pressure, high temperature refrigerant issupplied through pipe 276 to expansion valves 277 and 278 forrefrigerant metering (throttling) into evaporators 264 and 265. Once theheat is absorbed by the liquid refrigerant inside the evaporators 264and 265 the liquid refrigerant changes state into a gas, it is returnedto the compressor in the condensing unit 263 through return pipe 279where it is compressed and re-condensed into a liquid refrigerant forrecirculation. The condensing unit 263 shown in FIG. 118 can be awater-cooled heat pump unit with cooling and heating modes of operation.

FIG. 119 shows an air conditioning system employing three coaxial-flowheat transfer structures of the present invention 311, 312 and 313,which function as a heat transfer sub-system connected to a water towater air conditioning unit 281 with hydronic cooling coils 296 and 297.The heat transfer fluid being pumped by pump 291 through thecoaxial-flow heat transfer structures 311, 312 and 313 first leaves thewater cooled condenser section 280 through pipe 289 passing through ahydronic air vent 290, to remove air that might be in the fluid pipingsystem. In the cooling mode during times when the outdoor airtemperature is higher than the heat transfer fluid entering thecoaxial-flow heat transfer structures, through pipe 285, valve 284 isopen and valve 283 is closed. When the outdoor air temperature is belowthe temperature of the heat transfer fluid valve 284 is closed and valve283 is open allowing the heat transfer fluid to flow through outdoor airheat exchanger 282 allowing heat to be extracted from the heat transferfluid before into the ambient air before it enters the ground sourcewells through pipe 285. This function increases the heat transferefficiency of the entire system and promotes heat recovery time of thecoaxial-flow heat transfer structures and extending the overall life ofthe ground loop wells. The outdoor air heat exchanger 282 can beconstructed without a fan (i.e. natural draft) or with a fan (i.e.forced draft).

In the cooling mode, heat is extracted from the heat transfer fluid asit passes through the coaxial-flow heat transfer structures 311, 312 and313 124C. The heat transfer fluid leaving coaxial-flow heat transferstructure 311 is transferred to coaxial-flow heat transfer structure 312by pipe 286 where more heat is extracted from the heat transfer fluid.The heat transfer fluid leaving coaxial-flow heat transfer structure 312is transferred to coaxial-flow heat transfer structure 313 by pipe 287where more heat is extracted from the heat transfer fluid. The heattransfer fluid is returned to the condenser section 281 of the airconditioning heat pump. Heat contained in the heat transfer fluidentering the evaporator section 292 of the air conditioning heat pump istransferred to the condenser section 280 using a conventionalrefrigeration compressor and associated valves and piping. The heattransfer fluid entering the condenser section absorbs heat as it passesthrough the water cooled condenser section 280 and moves the heat intothe coaxial-flow heat transfer structures 311, 312 and 313. Thecirculation of the heat transfer fluid can be continuous or cyclicdepending on the application. The heat transfer fluid direction of flowcan be reversed entering the ground source wells through pipe 288 andexiting the wells through pipe 285.

During operation of the system, heat is absorbed by the heat transferfluid circulated heat exchangers 297 and 298. Heat is extracted from theheat transfer fluid in the evaporator section 292 of the airconditioning heat pump 281. The heat transfer fluid is pumped from theevaporator section 292 by pump 293. From the pump 293, the fluid passesthrough hydronic air vent 295 which removes air that might be in theheat transfer fluid. From the hydronic air vent, the heat transfer fluidenters a thermal storage tank 295 which adds to the internal heattransfer fluid volume of the system. The amount or internal volume ofheat transfer fluid is determined by the amount of heat being absorbedby heat exchangers 296 and 297 as opposed to the amount of heat that theair conditioning heat pump 281 is capable of transferring. In responseto the set point of temperature and conditions within the conditionedspaces, a typical thermostat activates and deactivates the airconditioning heat pump. Heat exchangers 296 and 297 can be constructedwith a fan (i.e. forced draft) or without a fan (natural draft) and maybe of the type shown in FIGS. 80 through 87.

A digital control system can be employed to monitor and control theoperation of the system based on indoor and outdoor temperatures, andtemperatures of fluid entering and leaving the coaxial-flow heattransfer structures. Additionally, fans, blowers, compressors, flowmeters and flow controls can be monitored and controlled according to acomputer control program. Sensors integrated into the manufacture of thecoaxial-flow heat exchanging structure of the present invention can beinstalled at certain depths to further monitor and control heat transferfluid flow throughout the resulting system. In the event that water isused as the heat transfer fluid, additives can be added to the system toreduce the freezing temperature of the heat transfer fluid to preventslushing of the heat transfer fluid. Some heat transfer additives cancause a reduction in heat transfer fluid efficacy.

In the heating mode, heat is added to the heat transfer fluid as itpasses through ground coaxial-flow heat transfer structures 311, 312 and313. The heat transfer fluid leaving coaxial-flow heat transferstructure 311 is transferred to coaxial-flow heat transfer structure 312by pipe 286 where more heat is added to the heat transfer fluid. Theheat transfer fluid leaving coaxial-flow heat transfer structure 312 istransferred to coaxial-flow heat transfer structure 313 by pipe 287where more heat is added to the heat transfer fluid. The heat transferfluid is returned to the condenser section 281 of the air conditioningheat pump through pipe 288. In the heating mode, the air conditioningheat pump 281 is in reverse cycle where the condenser section 280 andevaporator section 292 interchange function, The condenser section 280begins to function like an evaporator absorbing heat from the heattransfer fluid and transferring the heat into the evaporator section 292which begins to function like a condenser using a conventionalrefrigeration compressor and associated valves and piping, deliveringthe heat into heat transfer fluid and exchangers 266 and 267 fortransfer into the conditioned space. The circulation of the heattransfer fluid can be continuous or cyclic depending on the application.The heat transfer fluid direction of flow can be reversed entering thecoaxial-flow heat transfer structures through pipe 288 and exiting thecoaxial-flow heat transfer structures through pipe 286. The heattransfer fluid normally flows in one direction through the coaxial-flowheat transfer structures and indoor heat exchangers 296 and 297. Certainapplications may require the addition of three-way valves to reverse thedirection of heat transfer fluid flow through the piping system.

FIG. 120 is a schematic representation of a RF (or microwave)transmission/reception tower 301, next to the accompanying base stationhousing 299 (i.e. shelter) containing sensitive electronic equipmentconnected to antennae 300 by cable 302 and within an environment that isthermally controlled by an air conditioner 303 employing a plurality ofcoaxial-flow heat transfer structures 1 of the present inventioninstalled in a plurality of vertical well bores, using thermallyconductive cement and connected together in series with piping 305, 306and 307.

Also, it is understood that the coaxial-flow heat transfer structure ofthe present invention can be readily modified and employing in heat-pipesystems employed in diverse applications from ground-based heat pipes,or thermal management systems in laptop computers. In such an embodimentof the present invention, a coaxial-flow heat transfer structure asillustrated conceptually in FIG. 2 has a proximal end and a distal endwhich would be installed within an ambient environment having adifferential in temperature between the proximal and distal ends. Theinput and output ports of the structure would be sealed off or otherwiseinterconnected, after the inner and outer flow channels have beenproperly charged (i.e. filled) with an appropriate volume of heattransferring fluid (e.g. multi-phase fluid). Wicking or other fluidabsorptive material can be disposed along either or both the inner flowchannel as well as the helically-extending outer flow channel, formedbetween the inner and outer tube sections. The advantages of this heatpipe system design is that the length of the helically-extending outerflow channel can be made substantially longer that the length of theinner flow channel, providing more effective surface area and linearlength for the heat exchanging fluid to conduct heat energy along theouter flow channel.

While various illustrative embodiments of the present invention havebeen disclosed in great detail herein above, is understood that thecoaxial-flow heat-transfer technology employed in heat pump and transfersystems of the illustrative embodiments may be modified in a variety ofways which will become readily apparent to those skilled in the art ofhaving the benefit of the novel teachings disclosed herein. All suchmodifications and variations of the illustrative embodiments thereofshall be deemed to be within the scope and spirit of the presentinvention as defined by the Claims to Invention appended hereto.

1. A coaxial-flow heat transfer system comprising: athermally-conductive outer tube section, and an inner tube sectionhaving an inner flow channel having a substantially uniform innerdiameter along its length and being coaxially installed within saidouter tube section supporting helically-arranged turbulence generatorfins on the outer surface of said inner tube section, so as to form atleast one helically-extending outer flow channel between said inner andouter tube sections, so that heat energy contained within a heatexchanging fluid flowing down said inner flow channel and along thehelically-arranged outer flow channel, is exchanged through the walls ofsaid outer tube section and into the ambient environment.
 2. Thecoaxial-flow heat exchanging structure of claim 1, wherein said outertube section is installed in a deviated well bore, is made from a metalmaterial, and has a smooth outer surface.
 3. The coaxial-flow heatexchanging structure of claim 2, wherein the deviated well bore isdrilled nearly horizontal in the aquifer zone to maximize heat transferinto the ground, and said thermally-conductive outer tube section isgrouted (i.e. using thermally-conductive cement) to surface to preventaquifer contamination, and said deviated well bore employs a shortturning radius to deviate from vertical to near horizontal.
 4. Thecoaxial-flow heat exchanging structure of claim 1, wherein said innertube section supports, on its outer surface, multiple sets ofhelically-extending fins for use in creating a doublehelically-extending outer flow channel between said inner tube sectionand said thermally-conductive outer tube section.
 5. The coaxial-flowheat exchanging structure of claim 1, wherein a central tube section isinserted within said inner tube section with a gap space formedtherebetween for thermal insulation to the heat transferring fluidflowing along said inner flow channel of said inner tube section.
 6. Thecoaxial-flow heat exchanging structure of claim 1, wherein a singlehelically-extending fin for use in creating a single helically-extendingouter flow channel between said inner tube section and saidthermally-conductive outer tube section.
 7. The coaxial-flow heatexchanging structure of claim 6, wherein said gap space is filled withan insulation gas that is sealed within said gap space.
 8. Thecoaxial-flow heat exchanging structure of claim 7, wherein saidinsulation gas is selected from the group consisting of argon, nitrogen,and ethane.
 9. The coaxial-flow heat exchanging structure of claim 1,which further comprises a tubing shoe structure that is attached to thebottom of said helically-finned inner tube section, so as to protect thehelically-extending fins during installation.
 10. The coaxial-flow heatexchanging structure of claim 1, which when operated in a forward flowdirection, a heat exchanging fluid is pumped down said inner flowchannel of said inner tube section, and upon reaching the bottom of saidinner tube section, the fluid reverses its direction at the distalportion of said coaxial-flow heat transfer structure, and then flowsalong said helically-extending outer flow channel and out at theproximal end.
 11. The coaxial-flow heat exchanging structure of claim 1,which when operated in a reverse flow direction, wherein a heatexchanging fluid is pumped down the outer flow channel, where upon itreverses direction at the distal portion of the coaxial-flow heattransfer structure, and then flows along the inner flow channel and outat the proximal end.
 12. The coaxial-flow heat exchanging structure ofclaim 1, wherein said thermally-conductive outer tube section has afluted outer surface, and said inner tube section supports a singlehelically fin structure so as to provide a helically-extending outerflow channel that corresponds with the fluted surfaces along said outertube section.
 13. The coaxial-flow heat exchanging structure of claim 1,which supports a helical flow pattern of heat exchanging fluid as it ispumped down said helically-extending outer flow channel and flows upsaid inner flow channel.
 14. The coaxial-flow heat exchanging structureof claim 1, which supports a helical flow pattern of heat exchangingfluid as it is pumped down said inner flow channel and flows up saidcoaxially-arranged helically-extending outer flow channel.
 15. Thecoaxial-flow heat exchanging structure of claim 1, in combination with aconventional heat transfer equipment.
 16. The coaxial-flow heatexchanging structure of claim 1, wherein the cross-sectional dimensionsof said outer flow channel are selected/designed to produce fluid flowstherealong having optimal vortex characteristics that optimize heattransfer between said heat transfer fluid within said outer flow channeland the surface of said thermally-conductive outer tube section.
 17. Thecoaxial-flow heat exchanging structure of claim 16, wherein when theratio of the sides of the outer flow channel cross-section approaches1/1.1 (i.e. indicative of a square-like control volume), the resultingfluid flow through the outer flow channel will typically have one vortexfor flow rates of interest.
 18. The coaxial-flow heat exchangingstructure of claim 16, wherein when the ratio of the sides of the outerflow channel cross-section approaches 1/2.5 (i.e. indicative of arectangular-like control volume), the resulting fluid flow through theouter flow channel will typically have two vortices for flow
 19. Thecoaxial-flow heat exchanging structure of claim 16, wherein when theratio of the sides of the outer flow channel cross-section approaches1/4.0 (i.e. indicative of a rectangular-like control volume), theresulting fluid flow through the outer flow channel will typically havetwo vortices (one near each helical fin) with a laminar slot flow regionin the center region, for flow rates of interest.
 20. The coaxial-flowheat exchanging structure of claim 16, wherein said thermally-conductiveouter tube section has a corrugated surface, and a singlehelically-finned inner tube section, for producing a helically extendingouter flow channel along which turbulence is produced in the heatexchanging fluid flowing therealong.
 21. The coaxial-flow heatexchanging structure of claim 1, installed in a well bore in the Earth,and using a manifold cap at said proximal end, to securely hold saidhelically-finned inner tube section away from and off the bottom of saidthermally-conductive outer tube that has been grouted into the Earthwith a thermally-conductive cement.
 22. The coaxial-flow heat exchangingstructure of claim 1, wherein the fluid distribution through saidhelically-extending outer flow channel has a high degree of turbulence.23. The coaxial-flow heat exchanging structure of claim 1, wherein afluid return and injection manifold is provided at the proximal portionof said outer tube section.
 24. The coaxial-flow heat exchangingstructure of claim 23, wherein said fluid return and injection manifoldcomprises a cap structure installed on the proximal end of said outertube section.
 25. The coaxial-flow heat exchanging structure of claim24, wherein said cap structure comprises a compression-ring.
 26. Thecoaxial-flow heat exchanging structure of claim 24, wherein said capstructure comprises an O-ring or a U-ring seal around the proximalportion of the outer tube section, so as to prevent fluid leaks.
 27. Thecoaxial-flow heat exchanging structure of claim 24, wherein said capstructure comprises a clamped-type cap structure.
 28. The coaxial-flowheat exchanging structure of claim 24, wherein said fluid return andinjection manifold is joined to a plurality of small holes formed insaid cap structure so that heat exchanging fluid exits perpendicular tocentral axis of said outer tube section.
 29. The coaxial-flow heatexchanging structure of claim 24, wherein said fluid return andinjection manifold is joined to a plurality of small holes formed insaid cap structure so that heat exchanging fluid exits parallel tocentral axis of said outer tube section.
 30. The coaxial-flow heatexchanging structure of claim 1, which is installed in concrete pilingor pier installations.
 31. The coaxial-flow heat exchanging structure ofclaim 1, which is installed in foundation installations.
 32. Thecoaxial-flow heat exchanging structure of claim 1, wherein a pair oftube fittings are welded or fused to the side of said outer tubesection, for the injection and returning heat exchanging fluids to saidinner and outer flow channels.